HVAC Error Code Lookup: What Your Furnace or AC Code Means
Last updated: November 2, 2026 · Published by Colton Air Conditioning, NV license 0092120
Pick your brand, then your code, to see what the manufacturer's manual says it means and when to call. The list covers Amana, American Standard, Carrier, Goodman, Lennox and Trane. We list only codes we've checked against the manufacturer's own documents, for the model families named. Codes on other models can mean something different, so match the model on your equipment's data plate. Goodman and Amana ComfortBridge heat pumps share one code list. Rows marked Status (normal) are normal operation, not faults.
If you smell gas, leave the house and call Southwest Gas or 911 from outside.
All codes in one table
Brand guides: Amana guide Lennox guide.
| Code | What the manual says | When to call |
|---|---|---|
| Amana: ComfortBridge AC and heat pump codes | ||
| E15 | Low pressure (frequent low pressure faults). Amana lists a stop valve not fully open, a refrigerant line restriction, low charge or a leak, a low pressure sensor problem, an indoor fan motor issue, a faulty TXV or a faulty control board. | Leaks and charge are EPA-certified refrigerant work. Write down the exact code. If it keeps coming back or the system isn't heating or cooling, book online or call (702) 738-6976 to schedule. Book online or call (702) 738-6976 to schedule. |
| E11 | Run system test. The required startup system test is incomplete or running. Amana calls it a message only. | This is a startup message, not a fault. If it stays on after the installer's startup test, call us. Write down the exact code. If it keeps coming back or the system isn't heating or cooling, book online or call (702) 738-6976 to schedule. Book online or call (702) 738-6976 to schedule. |
| b9 | Low indoor airflow (minor). Amana lists a fan/motor obstruction, restrictive or undersized ductwork, or indoor motor failure. | Write down the exact code. If it keeps coming back or the system isn't heating or cooling, book online or call (702) 738-6976 to schedule. Book online or call (702) 738-6976 to schedule. |
| E5 | Blown fuse / fuse open. The fuse is blown, or a connector is open. | Don't open the electrical panel. Inverter units hold stored voltage. Write down the exact code. If it keeps coming back or the system isn't heating or cooling, book online or call (702) 738-6976 to schedule. Book online or call (702) 738-6976 to schedule. |
| d0 / d1 | Data not on network / invalid data on network. Shared data is missing or wrong on the network. | Write down the exact code. If it keeps coming back or the system isn't heating or cooling, book online or call (702) 738-6976 to schedule. Book online or call (702) 738-6976 to schedule. |
| 77 | Indoor unit to thermostat communication error. Communication between the indoor unit and the thermostat. | Write down the exact code. If it keeps coming back or the system isn't heating or cooling, book online or call (702) 738-6976 to schedule. Book online or call (702) 738-6976 to schedule. |
| A2 | Outdoor air temp sensor fault | This is a sensor fault. Write down the exact code and have a licensed tech check the sensor and its wiring. Book online or call (702) 738-6976 to schedule. |
| A3 | Outdoor coil temp sensor fault | This is a sensor fault. Write down the exact code and have a licensed tech check the sensor and its wiring. Book online or call (702) 738-6976 to schedule. |
| EE | Board mis-operation | This is a control or communication fault. Write down the exact code and have a licensed tech check the control setup. Book online or call (702) 738-6976 to schedule. |
| d2 | System mis-match | This is a control or communication fault. Write down the exact code and have a licensed tech check the control setup. Book online or call (702) 738-6976 to schedule. |
| 01 | Low side fault | Pressure faults need EPA-certified refrigerant work. Write down the exact code and have a licensed tech check the system. Book online or call (702) 738-6976 to schedule. |
| L1 | Low pressure cut out lockout (3 trips) | This is a lockout. Don't keep clearing it. Write down the exact code and have a licensed tech check the system. Book online or call (702) 738-6976 to schedule. |
| 02 | High side fault | Pressure faults need EPA-certified refrigerant work. Write down the exact code and have a licensed tech check the system. Book online or call (702) 738-6976 to schedule. |
| L2 | High pressure cut out | Pressure faults need EPA-certified refrigerant work. Write down the exact code and have a licensed tech check the system. Book online or call (702) 738-6976 to schedule. |
| 03 | Short cycling | Write down the exact code. If it keeps coming back or the system isn't heating or cooling, have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| 04 | Locked rotor | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| 05 | Open circuit | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| 06 | Open start circuit | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| H8 | High line voltage | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| 09 | Low pilot voltage | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| P0 | Compressor protector open | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| L8 | Low line voltage / no line voltage | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| Amana: AMVC96 gas furnace | ||
| IdL | Status (normal): Normal operation (idle) | Normal operation, not a fault. |
| d0 | Equipment lacks shared data | This is a control or data fault. Write down the exact code and have a licensed tech check the control setup. Book online or call (702) 738-6976 to schedule. |
| E0 | Circulator blower motor not running when it should be | This is a blower or airflow fault. Write down the exact code and have a licensed tech check the blower and its settings. Book online or call (702) 738-6976 to schedule. Related guide. |
| E1 | Control lost communications with circulator blower motor | This is a blower or airflow fault. Write down the exact code and have a licensed tech check the blower and its settings. Book online or call (702) 738-6976 to schedule. Related guide. |
| E2 | Blower motor horsepower in shared data set does not match motor | This is a blower or airflow fault. Write down the exact code and have a licensed tech check the blower and its settings. Book online or call (702) 738-6976 to schedule. Related guide. |
| E9 | Airflow lower than demanded | This is a blower or airflow fault. Write down the exact code and have a licensed tech check the blower and its settings. Book online or call (702) 738-6976 to schedule. Related guide. |
| E10 | Grounding fault / poor neutral connection | This is an electrical fault inside the furnace. Don't open the furnace panel. Write down the exact code and have a licensed tech check the wiring and control board. Book online or call (702) 738-6976 to schedule. |
| E11 | Open rollout switch | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| Ed0 | Data not yet on network | This is a control or data fault. Write down the exact code and have a licensed tech check the control setup. Book online or call (702) 738-6976 to schedule. |
| Ed1 | Invalid memory card data | This is a control or data fault. Write down the exact code and have a licensed tech check the control setup. Book online or call (702) 738-6976 to schedule. |
| EE0 | Lockout: excessive ignition retries (3), failure to establish flame, or flame lost after establishment | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| EE1 | Low-stage pressure switch circuit closed at start of heat / contacts sticking / short in wiring | This points to the venting, inducer or drain side of the furnace. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. Related guide. |
| EE2 | Low-stage pressure switch circuit not closed (blocked flue/inlet, blocked drain, weak inducer, hose issue) | This points to the venting, inducer or drain side of the furnace. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. Related guide. |
| EE9 | High-stage pressure switch circuit not closed; furnace runs on low stage only | This points to the venting, inducer or drain side of the furnace. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. Related guide. |
| EEA | Reversed 115V polarity or poor unit ground | This is an electrical fault inside the furnace. Don't open the furnace panel. Write down the exact code and have a licensed tech check the wiring and control board. Book online or call (702) 738-6976 to schedule. |
| EEC | Gas valve energized when it should not be (internal gas valve error) | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| American Standard: S9V2 S-Series 2-stage variable-speed furnace | ||
| E01 | Loss of IRQ or other internal control failure | This is an electrical fault inside the furnace. Don't open the furnace panel. Write down the exact code and have a licensed tech check the wiring and control board. Book online or call (702) 738-6976 to schedule. |
| E2.1 | Retry exceeded: flame never sensed; 1-hour lockout after 3 tries | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| E2.2 | Recycles exceeded: flame sensed then lost; 1-hour lockout after 10 | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| E2.3 | 1st-stage gas valve not energized when it should be (10 times) | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| E3.1 | Shorted pressure switch, 1st stage | This points to the venting, inducer or drain side of the furnace. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. Related guide. |
| E3.2 | Open pressure switch, 1st stage | This points to the venting, inducer or drain side of the furnace. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. Related guide. |
| E3.3 | Shorted pressure switch, 2nd stage | This points to the venting, inducer or drain side of the furnace. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. Related guide. |
| E3.4 | Open pressure switch, 2nd stage | This points to the venting, inducer or drain side of the furnace. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. Related guide. |
| E04 | Open limit (main thermal, rollout or reverse-airflow switch) | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| E05 | Flame detected when it should not be present | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| E6.1 | Reversed line-voltage polarity | This is an electrical fault inside the furnace. Don't open the furnace panel. Write down the exact code and have a licensed tech check the wiring and control board. Book online or call (702) 738-6976 to schedule. |
| E6.2 | Bad grounding | This is an electrical fault inside the furnace. Don't open the furnace panel. Write down the exact code and have a licensed tech check the wiring and control board. Book online or call (702) 738-6976 to schedule. |
| E6.3 | Igniter relay fails or igniter open | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| E7.1 | 1st-stage gas valve energized when it should be off | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| E08 | Low flame current, still enough to operate | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| E09 | Open inducer limit switch or condensate pressure switch | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| E11 | Gas valve / gas valve relay fault (stage 1 or 2 energized/not energized incorrectly, relay stuck closed) | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| E12 | Open fuse | This is an electrical fault inside the furnace. Don't open the furnace panel. Write down the exact code and have a licensed tech check the wiring and control board. Book online or call (702) 738-6976 to schedule. |
| E13 | Blower HP/OEM ID | This is a blower or airflow fault. Write down the exact code and have a licensed tech check the blower and its settings. Book online or call (702) 738-6976 to schedule. Related guide. |
| E14 | No PM and local copy bad | This is a control or data fault. Write down the exact code and have a licensed tech check the control setup. Book online or call (702) 738-6976 to schedule. |
| E15 | Both unit data files (PM and local) corrupt | This is a control or data fault. Write down the exact code and have a licensed tech check the control setup. Book online or call (702) 738-6976 to schedule. |
| E17 | Blower motor no communication response | This is a blower or airflow fault. Write down the exact code and have a licensed tech check the blower and its settings. Book online or call (702) 738-6976 to schedule. Related guide. |
| E18 | Blower communication failure on the control | This is a blower or airflow fault. Write down the exact code and have a licensed tech check the blower and its settings. Book online or call (702) 738-6976 to schedule. Related guide. |
| Carrier: 59SC5A gas furnace (status light flash codes) | ||
| 11 | No previous code (stored codes cleared) | This means no fault is stored. If the furnace still isn't heating, have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| 12 | Blower on after power up | Write down the exact code. If it keeps coming back or the furnace isn't heating, have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| 13 | Limit circuit lockout | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| 14 | Ignition lockout | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| 21 | Gas heating lockout | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| 22 | Abnormal flame-proving signal | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| 23 | Pressure switch did not open | This points to the venting, inducer or drain side of the furnace. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. Related guide. |
| 24 | Secondary voltage fuse is open | This is an electrical fault inside the furnace. Don't open the furnace panel. Write down the exact code and have a licensed tech check the wiring and control board. Book online or call (702) 738-6976 to schedule. |
| 31 | Low- or high-pressure switch did not close or reopened | This points to the venting, inducer or drain side of the furnace. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. Related guide. |
| 33 | Limit circuit fault (limit or flame rollout open) | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| 34 | Ignition proving failure | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| 45 | Control circuitry lockout | This is an electrical fault inside the furnace. Don't open the furnace panel. Write down the exact code and have a licensed tech check the wiring and control board. Book online or call (702) 738-6976 to schedule. |
| Carrier: 59TP6C gas furnace (display status) | ||
| iDl | Status (normal): Idle/standby | Normal operation, not a fault. |
| Ht1 | Status (normal): Low heating | Normal operation, not a fault. |
| Ht2 | Status (normal): High heating | Normal operation, not a fault. |
| CL1 | Status (normal): Low cooling | Normal operation, not a fault. |
| CL2 | Status (normal): High cooling | Normal operation, not a fault. |
| Hpd | Status (normal): Heat pump defrost (gas heat active) | Normal operation, not a fault. |
| Carrier: Performance 25HPA6 two-stage heat pump | ||
| 16 | System communications failure | This is a control or communication fault. Write down the exact code and have a licensed tech check the control setup. Book online or call (702) 738-6976 to schedule. |
| 25 | Invalid model plug | This is a control or communication fault. Write down the exact code and have a licensed tech check the control setup. Book online or call (702) 738-6976 to schedule. |
| 31 | High pressure switch trip or discharge temp switch trip | Pressure faults need EPA-certified refrigerant work. Write down the exact code and have a licensed tech check the system. Book online or call (702) 738-6976 to schedule. |
| 32 | Low pressure switch trip | Pressure faults need EPA-certified refrigerant work. Write down the exact code and have a licensed tech check the system. Book online or call (702) 738-6976 to schedule. |
| 45 | Control fault | This is a control or communication fault. Write down the exact code and have a licensed tech check the control setup. Book online or call (702) 738-6976 to schedule. |
| 46 | Brown out (230V) | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| 47 | No 230V with call to run | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| 53 | Outdoor air temp sensor | This is a sensor fault. Write down the exact code and have a licensed tech check the sensor and its wiring. Book online or call (702) 738-6976 to schedule. |
| 55 | Coil temp sensor | This is a sensor fault. Write down the exact code and have a licensed tech check the sensor and its wiring. Book online or call (702) 738-6976 to schedule. |
| 56 | Temp sensor range error | This is a sensor fault. Write down the exact code and have a licensed tech check the sensor and its wiring. Book online or call (702) 738-6976 to schedule. |
| 71 | Low stage thermal cutout | Write down the exact code. If it keeps coming back or the system isn't heating or cooling, have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| 72 | High stage thermal cutout | Write down the exact code. If it keeps coming back or the system isn't heating or cooling, have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| 73 | Contactor shorted | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| 74 | Contactor open (no 230V to compressor) | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| 81 | Low stage thermal lockout (4 hrs) | This is a lockout. Don't keep clearing it. Write down the exact code and have a licensed tech check the system. Book online or call (702) 738-6976 to schedule. |
| 82 | High stage thermal lockout (4 hrs) | This is a lockout. Don't keep clearing it. Write down the exact code and have a licensed tech check the system. Book online or call (702) 738-6976 to schedule. |
| 83 | Low pressure lockout (4 hrs) | This is a lockout. Don't keep clearing it. Write down the exact code and have a licensed tech check the system. Book online or call (702) 738-6976 to schedule. |
| 84 | High pressure lockout (4 hrs) | This is a lockout. Don't keep clearing it. Write down the exact code and have a licensed tech check the system. Book online or call (702) 738-6976 to schedule. |
| Goodman: GR9S96 / GD9S96 gas furnace | ||
| EEE | Internal faults or IRQ loss | This is an electrical fault inside the furnace. Don't open the furnace panel. Write down the exact code and have a licensed tech check the wiring and control board. Book online or call (702) 738-6976 to schedule. |
| EE0 | Lockout due to excessive retries/recycles | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| EE1 | Pressure switch stuck closed | This points to the venting, inducer or drain side of the furnace. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. Related guide. |
| EE2 | Pressure switch open | This points to the venting, inducer or drain side of the furnace. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. Related guide. |
| EE3 | Open high limit switch | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| EE4 | Flame detected when no flame should be present | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| EE5 | Open fuse | This is an electrical fault inside the furnace. Don't open the furnace panel. Write down the exact code and have a licensed tech check the wiring and control board. Book online or call (702) 738-6976 to schedule. |
| EE6 | Low flame signal | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| EEL | Igniter relay fault | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| EEA | Reversed line polarity or grounding error | This is an electrical fault inside the furnace. Don't open the furnace panel. Write down the exact code and have a licensed tech check the wiring and control board. Book online or call (702) 738-6976 to schedule. |
| EEb | Internal gas valve error | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| EEC | External gas valve error | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| E11 | Open rollout switch | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| EEn | Igniter open | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| EEJ | Inducer relay error | This points to the venting, inducer or drain side of the furnace. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. Related guide. |
| EEH | Twin error | Write down the exact code. If it keeps coming back or the furnace isn't heating, have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| E10 | Grounding error | This is an electrical fault inside the furnace. Don't open the furnace panel. Write down the exact code and have a licensed tech check the wiring and control board. Book online or call (702) 738-6976 to schedule. |
| EbL | Low circulator current | This is a blower or airflow fault. Write down the exact code and have a licensed tech check the blower and its settings. Book online or call (702) 738-6976 to schedule. Related guide. |
| EbU | Circulator current unexpected | This is a blower or airflow fault. Write down the exact code and have a licensed tech check the blower and its settings. Book online or call (702) 738-6976 to schedule. Related guide. |
| EAF | A2L (refrigerant sensor) communication alarm | This is a refrigerant leak sensor alarm. Leak work is EPA-certified refrigerant work. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| EAL | A2L refrigerant leakage alarm | This is a refrigerant leak sensor alarm. Leak work is EPA-certified refrigerant work. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| EAS | A2L internal alarm | This is a refrigerant leak sensor alarm. Leak work is EPA-certified refrigerant work. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| EAr | A2L relay alarm | This is a refrigerant leak sensor alarm. Leak work is EPA-certified refrigerant work. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| Goodman: ComfortBridge two-stage heat pump (Goodman/Amana shared codes) | ||
| A2 | Outdoor air temp sensor fault | This is a sensor fault. Write down the exact code and have a licensed tech check the sensor and its wiring. Book online or call (702) 738-6976 to schedule. |
| A3 | Outdoor coil temp sensor fault | This is a sensor fault. Write down the exact code and have a licensed tech check the sensor and its wiring. Book online or call (702) 738-6976 to schedule. |
| E5 | Open fuse | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| EE | Board mis-operation | This is a control or communication fault. Write down the exact code and have a licensed tech check the control setup. Book online or call (702) 738-6976 to schedule. |
| d0 | Data not yet on network | This is a control or communication fault. Write down the exact code and have a licensed tech check the control setup. Book online or call (702) 738-6976 to schedule. |
| d1 | Invalid data on network | This is a control or communication fault. Write down the exact code and have a licensed tech check the control setup. Book online or call (702) 738-6976 to schedule. |
| d2 | System mis-match | This is a control or communication fault. Write down the exact code and have a licensed tech check the control setup. Book online or call (702) 738-6976 to schedule. |
| 01 | Low side fault | Pressure faults need EPA-certified refrigerant work. Write down the exact code and have a licensed tech check the system. Book online or call (702) 738-6976 to schedule. |
| L1 | Low pressure cut out lockout (3 trips) | This is a lockout. Don't keep clearing it. Write down the exact code and have a licensed tech check the system. Book online or call (702) 738-6976 to schedule. |
| 02 | High side fault | Pressure faults need EPA-certified refrigerant work. Write down the exact code and have a licensed tech check the system. Book online or call (702) 738-6976 to schedule. |
| L2 | High pressure cut out | Pressure faults need EPA-certified refrigerant work. Write down the exact code and have a licensed tech check the system. Book online or call (702) 738-6976 to schedule. |
| 03 | Short cycling | Write down the exact code. If it keeps coming back or the system isn't heating or cooling, have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| 04 | Locked rotor | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| 05 | Open circuit | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| 06 | Open start circuit | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| H8 | High line voltage | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| 09 | Low pilot voltage | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| P0 | Compressor protector open | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| L8 | Low line voltage / no line voltage | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| Lennox: Thermostat alert codes (outdoor unit) | ||
| 105 | Wiring Issue / Communication Problem. A communication problem between components. | Write down the exact code. If it keeps coming back or the system isn't heating or cooling, book online or call (702) 738-6976 to schedule. Book online or call (702) 738-6976 to schedule. |
| 400 | OD LSOM Comp. Internal Overload Tripped. The compressor's internal overload tripped: there is a cooling demand, but the compressor is not running. | Write down the exact code. If it keeps coming back or the system isn't heating or cooling, book online or call (702) 738-6976 to schedule. Book online or call (702) 738-6976 to schedule. |
| 401 | OD Compressor Long Run Cycle. The compressor ran more than 18 hours straight on a single cooling demand, or refrigerant pressure is low. | Low refrigerant pressure needs EPA-certified refrigerant work. Write down the exact code. If it keeps coming back or the system isn't heating or cooling, book online or call (702) 738-6976 to schedule. Book online or call (702) 738-6976 to schedule. |
| 402 | OD System Pressure Trip. Discharge or suction pressure is out of limits, or the compressor overloaded. | Pressure faults need EPA-certified refrigerant work. Write down the exact code. If it keeps coming back or the system isn't heating or cooling, book online or call (702) 738-6976 to schedule. Book online or call (702) 738-6976 to schedule. |
| 403 | OD Compressor Short-Cycling. The compressor ran less than three minutes to satisfy a thermostat demand. | Write down the exact code. If it keeps coming back or the system isn't heating or cooling, book online or call (702) 738-6976 to schedule. Book online or call (702) 738-6976 to schedule. |
| 404 | OD Compressor Rotor Locked. Locked rotor, which Lennox lists as a run capacitor short, seized bearings or excessive liquid refrigerant. | Don't open the electrical panel. Capacitor and compressor faults are electrical work. Write down the exact code. If it keeps coming back or the system isn't heating or cooling, book online or call (702) 738-6976 to schedule. Book online or call (702) 738-6976 to schedule. |
| 411 | OD Low Pressure Switch Strikes Lockout. The low pressure switch opened five times in one demand, and the thermostat shuts the outdoor unit down. | This is a lockout. Don't keep clearing it. Lennox's fixes involve refrigerant pressures, which is EPA-certified work. Write down the exact code. If it keeps coming back or the system isn't heating or cooling, book online or call (702) 738-6976 to schedule. Book online or call (702) 738-6976 to schedule. |
| 413 | OD High Pressure Switch Strikes Lockout. The high pressure switch opened five times in one cooling demand, and the outdoor unit shuts down. | This is a lockout. Don't keep clearing it. Lennox's fixes involve refrigerant pressures, which is EPA-certified work. Write down the exact code. If it keeps coming back or the system isn't heating or cooling, book online or call (702) 738-6976 to schedule. Book online or call (702) 738-6976 to schedule. |
| 414 | OD High Discharge Line Temperature. Discharge line temperature is above 279°F. | High discharge temperature needs EPA-certified refrigerant work. Write down the exact code. If it keeps coming back or the system isn't heating or cooling, book online or call (702) 738-6976 to schedule. Book online or call (702) 738-6976 to schedule. |
| Lennox: ML180UH Merit gas furnace | ||
| Red slow / Green slow (simultaneous) | Status (normal): Power on, normal operation (also cooling and continuous fan) | Normal operation, not a fault. |
| Red fast / Green fast (simultaneous) | Status (normal): Heating demand initiated | Normal operation, not a fault. |
| Red slow / Green on | Primary or secondary limit open; 1-hour Watchguard if not closed in 3 min | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| Red off / Green slow | Pressure switch open, blocked inlet/exhaust vent, or switch closed before inducer starts | This points to the venting, inducer or drain side of the furnace. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. Related guide. |
| Red slow / Green slow (alternating) | Watchguard 1 hour: failed to ignite or lost flame 5 times in one demand | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| Red slow / Green off | Flame sensed without gas valve energized | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| Red on / Green slow | Rollout switch open or 12-pin connector improperly attached | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| Red on/Green on, Red on/Green off, Red off/Green on | Circuit board failure or control wired incorrectly | This is an electrical fault inside the furnace. Don't open the furnace panel. Write down the exact code and have a licensed tech check the wiring and control board. Book online or call (702) 738-6976 to schedule. |
| Red fast / Green slow | Main power polarity reversed | This is an electrical fault inside the furnace. Don't open the furnace panel. Write down the exact code and have a licensed tech check the wiring and control board. Book online or call (702) 738-6976 to schedule. |
| Red slow / Green fast | Low flame signal (below 1.5 microamps) | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| Red fast / Green fast (alternating) | Improper main ground or line voltage below 90 V | This is an electrical fault inside the furnace. Don't open the furnace panel. Write down the exact code and have a licensed tech check the wiring and control board. Book online or call (702) 738-6976 to schedule. |
| Lennox: SL25XPV variable-capacity heat pump (outdoor display) | ||
| E120 | Delay in outdoor unit responding to the system | Write down the exact code. If it keeps coming back or the system isn't heating or cooling, have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| E124 | S30 thermostat lost communication with outdoor unit for more than 3 minutes | This is a control or communication fault. Write down the exact code and have a licensed tech check the control setup. Book online or call (702) 738-6976 to schedule. |
| E125 | Hardware problem with the outdoor control | This is a control or communication fault. Write down the exact code and have a licensed tech check the control setup. Book online or call (702) 738-6976 to schedule. |
| E131 | Outdoor unit control parameters corrupted | This is a control or communication fault. Write down the exact code and have a licensed tech check the control setup. Book online or call (702) 738-6976 to schedule. |
| E132 | Internal software error | This is a control or communication fault. Write down the exact code and have a licensed tech check the control setup. Book online or call (702) 738-6976 to schedule. |
| E180 | Outdoor ambient temperature sensor malfunctioned; no low ambient cooling | This is a sensor fault. Write down the exact code and have a licensed tech check the sensor and its wiring. Book online or call (702) 738-6976 to schedule. |
| E181 | Suction pressure transducer fault | Pressure faults need EPA-certified refrigerant work. Write down the exact code and have a licensed tech check the system. Book online or call (702) 738-6976 to schedule. |
| E182 | Suction temperature sensor malfunctioned | This is a sensor fault. Write down the exact code and have a licensed tech check the sensor and its wiring. Book online or call (702) 738-6976 to schedule. |
| E183 | Liquid pressure transducer fault | Pressure faults need EPA-certified refrigerant work. Write down the exact code and have a licensed tech check the system. Book online or call (702) 738-6976 to schedule. |
| E345 | O relay on board failed | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| E409 | Outdoor control secondary voltage 18VAC or less | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| E410 | Outdoor unit cycled off due to low suction pressure | Pressure faults need EPA-certified refrigerant work. Write down the exact code and have a licensed tech check the system. Book online or call (702) 738-6976 to schedule. |
| E412 | Outdoor unit high pressure switch opened | Pressure faults need EPA-certified refrigerant work. Write down the exact code and have a licensed tech check the system. Book online or call (702) 738-6976 to schedule. |
| E416 | Outdoor coil sensor malfunctioned | This is a sensor fault. Write down the exact code and have a licensed tech check the sensor and its wiring. Book online or call (702) 738-6976 to schedule. |
| E422 | Compressor top cap switch exceeding thermal limit | Write down the exact code. If it keeps coming back or the system isn't heating or cooling, have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| E423 | Inverter detected a circuit problem | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| E424 | Liquid line temperature sensor malfunctioned | This is a sensor fault. Write down the exact code and have a licensed tech check the sensor and its wiring. Book online or call (702) 738-6976 to schedule. |
| E425 | Compressor speed increased for oil return due to low ambient temperature (info only) | This is an information message from the outdoor unit, not a lockout. If the system isn't heating or cooling, have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| E426 | Excessive inverter alarms | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| E427 | Inverter detected a DC peak fault condition | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| E428 | Inverter detected a high main input current condition | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| E429 | DC link power in inverter did not rise to required voltage | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| E430 | Compressor start failure | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| E431 | PFC over-current condition | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| E432 | Inverter detected a DC link high voltage condition | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| E433 | Inverter detected a compressor over-current condition | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| E434 | Outdoor control lost communications with the inverter for more than 3 minutes | This is a control or communication fault. Write down the exact code and have a licensed tech check the control setup. Book online or call (702) 738-6976 to schedule. |
| E435 | Inverter internal error | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| E436 | Inverter heat sink temperature exceeded limit | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| E437 | Heat sink temperature sensor fault | This is a sensor fault. Write down the exact code and have a licensed tech check the sensor and its wiring. Book online or call (702) 738-6976 to schedule. |
| E438 | Inverter detected a PFC over current condition | This is an electrical fault in the outdoor unit. Don't open the electrical panel; inverter units can hold stored voltage. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| E439 | Compressor slowdown due to high input current (info only) | This is an information message from the outdoor unit, not a lockout. If the system isn't heating or cooling, have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| E440 | Heat sink temperature approaching limit; compressor slows (info only) | This is an information message from the outdoor unit, not a lockout. If the system isn't heating or cooling, have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| E441 | Compressor slowdown due to high compressor current (info only) | This is an information message from the outdoor unit, not a lockout. If the system isn't heating or cooling, have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| E442 | Top cap switch opened five times within one hour; outdoor unit locked out | This is a lockout. Don't keep clearing it. Write down the exact code and have a licensed tech check the system. Book online or call (702) 738-6976 to schedule. |
| E443 | Incorrect appliance unit size code selected | This is a control or communication fault. Write down the exact code and have a licensed tech check the control setup. Book online or call (702) 738-6976 to schedule. |
| E600 | Compressor cycled OFF on utility load shedding (info only) | This is an information message from the outdoor unit, not a lockout. If the system isn't heating or cooling, have a licensed tech check it. Book online or call (702) 738-6976 to schedule. |
| Trane: S9X1 / S9X2 / S9B1 gas furnace | ||
| E01 | Internal failure of the control board | This is an electrical fault inside the furnace. Don't open the furnace panel. Write down the exact code and have a licensed tech check the wiring and control board. Book online or call (702) 738-6976 to schedule. |
| E2.1 | Retry lockout: 3 unsuccessful ignition tries in one call; 1-hour lockout | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| E2.2 | Recycle lockout: 10 recycles in one call; 1-hour lockout | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| E2.3 | 1st-stage gas valve not energized when it should be (10 times in one call) | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| E3.1 | Pressure switch PS1 closed when it should be open | This points to the venting, inducer or drain side of the furnace. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. Related guide. |
| E3.2 | Pressure switch PS1 open when it should be closed | This points to the venting, inducer or drain side of the furnace. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. Related guide. |
| E3.3 | Pressure switch PS2 closed when it should be open | This points to the venting, inducer or drain side of the furnace. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. Related guide. |
| E3.4 | Pressure switch PS2 open when it should be closed | This points to the venting, inducer or drain side of the furnace. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. Related guide. |
| E04 | Limit switch open (abnormal high temperature) | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| E05 | Flame sensed when it should not be | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| E6.1 | Polarity fault: incoming high-voltage wiring reversed | This is an electrical fault inside the furnace. Don't open the furnace panel. Write down the exact code and have a licensed tech check the wiring and control board. Book online or call (702) 738-6976 to schedule. |
| E6.2 | Ground fault: incoming or chassis ground not sensed | This is an electrical fault inside the furnace. Don't open the furnace panel. Write down the exact code and have a licensed tech check the wiring and control board. Book online or call (702) 738-6976 to schedule. |
| E6.3 | Igniter relay fault (relay stuck closed) | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| E7.1 | External gas valve circuit error | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| E08 | Flame sense current below 0.5 microamp DC | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| E09 | Condensate pressure switch open | This points to the venting, inducer or drain side of the furnace. Write down the exact code and have a licensed tech check it. Book online or call (702) 738-6976 to schedule. Related guide. |
| E11 | Internal gas valve relays have failed | If you smell gas, leave the house and call Southwest Gas or 911 from outside. Otherwise, write down the exact code and have a licensed tech check the burner and safety controls. Book online or call (702) 738-6976 to schedule. Related guide. |
| E12 | Onboard 5-amp fuse open or missing | This is an electrical fault inside the furnace. Don't open the furnace panel. Write down the exact code and have a licensed tech check the wiring and control board. Book online or call (702) 738-6976 to schedule. |
Book online or call (702) 738-6976 to schedule.