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Error code reference
Lennox Furnace Error Codes
182 error codes documented with diagnostic procedures.
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1Reverse line voltage polarity.1 FlashFlame present with gas valve de-energized (control 103085).1+2Low flame current during run mode (Board 100869).1+3Flame sensed out of sequence10Watchguard11Pressure switch stuck closed prior to activation of combustion air inducer.2Improper Earth Ground.2 FlashesPressure switch closed with combustion air inducer de-energized (control 103085).2 Flashes (RAM)Control lockout2+3Low fire pressure switch sensed open; 80%2+4Low fire pressure switch sensed closed prior to activation of combustion air inducer.2+5High fire pressure switch sensed open. 80%2+6High fire pressure switch sensed closed prior to activation of combustion air inducer.2+7Low pressure switch opened during ignition trial or heating demand (Board 100869).3Burner failed to light, or lost flame during heat demand.3 FlashesPressure switch open with combustion air inducer energized (Control 103085).3 Flashes (RAM)Pressure switch open3+1Primary / Secondary limit switch open.4Low Flame Signal4 FlashesPrimary limit switch open (Control 103085).4 Flashes (RAM)Open limit4+1Watchguard4+2Watchguard4+3Watchguard4+5Watchguard4+6Watchguard4+7Watchguard4+8Watchguard5Watchguard5 FlashesRollout switch open (control 103085).5 Flashes (RAM)Flame sensed and gas valve not energized.5+1Hard lockout5+2Control failed self check, internal error; control will restart if error recovers (Board…5+3No Earth ground; control will restart if error recovers (Board 100869).5+4Reversed line voltage polarity; control will restart if the error recovers (Board 100869).5+5Low 24V (control will restart if voltage rises to normal).5+6Low secondary (24VAC) voltage (Board 100870).6 FlashesPressure switch cycle lockout (control 103085).7Primary or Secondary Limit Open or Watchguard Mode7 FLASHESLockout8Rollout Switch Open.8 FlashesLockout9Pressure Switch failed to close or opened during heat demand.9 FlashesLine voltage polarity incorrect (Control 103085).DIAG#1: Alternate Flash / DIAG#2: Alternate FlashWatchguardDIAG#1: Continuous On / DIAG#2: Continuous OnCircuit board self-check failure or ignition/blower control is wired incorrectly.DIAG#1: Flash / DIAG#2: OffPressure switch WatchguardDIAG#1: Off / DIAG#2: FlashFlame sensed without gas valve energized.DIAG#1: On / DIAG#2: FlashPrimary or secondary limit switch open (auto-reset switch).DIAG#1: Simultaneous Flash / DIAG#2: Simultaneous FlashPower ON, normal operation; increased flash rate indicates a heating demand.DS1 Alternating Fast Flash / DS2 Alternating Fast FlashDuring ignitor warm-up period onlyDS1 Alternating Slow Flash / DS2 Alternating Slow FlashWatchguardDS1 Fast Flash / DS2 Fast FlashNormal operationDS1 Fast Flash / DS2 Fast Flash (simultaneous)Normal operationDS1 Fast Flash / DS2 Slow FlashDuring ignitor warm-up period onlyDS1 OFF / DS2 Fast FlashHigh pressure switch open; OR blocked inlet/exhaust vent; OR high pressure switch closed…DS1 Off / DS2 OnLow flame signal; measures below 0.23 microAmpsDS1 OFF / DS2 Slow FlashLow pressure switch open (G32V-75 only); OR blocked inlet/exhaust vent; OR low pressure…DS1 ON / DS2 OFFMain power polarity reversedDS1 ON / DS2 ONCircuit board failure or control wired incorrectlyDS1 Simultaneous Fast Flash / DS2 Simultaneous Fast FlashNormal operationDS1 Simultaneous Slow Flash / DS2 Simultaneous Slow FlashPower onDS1 Slow Flash / DS2 Fast FlashLow flame signal. Measures below 0.23 microAmps. Replace flame sense rod. (G32V-5 unitsDS1 Slow Flash / DS2 OFFFlame sensed without gas valve energizedDS1 Slow Flash / DS2 ONPrimary, secondary, backup secondary or rollout limit switch open; limits must close…DS1 Slow Flash / DS2 Slow FlashPower onDS1 Slow Flash / DS2 Slow Flash (simultaneous)Power onDS1/DS2 Alternating Fast FlashDuring ignitor warm-up onlyDS1/DS2 Alternating Slow FlashWatchguardE 125Control failed self-check, internal error, failed hardware (flame sense circuit faults…E 223Low pressure switch failed open.E 226High pressure switch failed closed.E 227Low pressure switch open during trial for ignition or run mode.E 240Low flame current during run mode.E 250Limit switch circuit open.E 271Soft lockoutE 272Soft lockoutE 273Soft lockoutE 274Soft lockoutE 290Ignitor circuit faultE105Device communication problemE110Low line voltage detected (voltage lower than nameplate rating).E111Line voltage polarity reversed.E112Ground not detected; system shuts down.E113High line voltage detected (voltage higher than nameplate rating).E114Line voltage frequency out-of-range (no 60 Hertz power).E115Low 24V power (range is 18 to 30 volts); control will restart if the error recovers.E116High 24V (range is 18 to 30 volts).E117Poor ground detected (warning only).E120Unresponsive device (communication only), usually caused by delay in outdoor unit…E124Active communicating thermostat signal missing for more than 3 minutes.E126Control internal communication problem.E131Corrupted control parameters (communicating only).E180Outdoor air temperature sensor failure (shorted or out-of-range).E200Hard lockoutE201Indoor blower communication failureE202Indoor blower motor mis-matchE203Appliance capacity/size is NOT programmed; invalid unit codes.E204High line voltage (voltage higher than nameplate rating).E205Gas valve control relay contact shorted.E206Gas valve second-stage relay failure.E207Hot surface ignitor sensed open.E210Unresponsive device.E224Low pressure switch failed closed (stuck closed on heat call longer than 150 seconds).E225Gas valve control relay contact shorted.E228Unable to perform successful pressure switch calibration.E229Ignition on High FireE241Flame sensed out of sequenceE252Discharge air temperature too high (gas heat only).E270Soft lockoutE275Heat rate reduced to match indoor blower air flow; replace filter or repair duct…E276Watchguard calibration failure.E291Heat air flow restricted below the minimum.E292Indoor blower motor unable to start due to obstructed wheel or seized bearings.E294Combustion air inducer over current.E295Indoor blower motor temperature is too high (motor tripped on internal protector).E310Discharge air temperature sensor failure (shorted or out of range).E311Heat rate reduced to match indoor blower air flow (furnace blower in cutback mode due to…E312Restricted air flow in cooling or continuous fan mode is lower than cfm setting (cutback…E313Indoor or outdoor unit capacity mismatch (communication only).E331Global network connectionE334Relay Y1 stuck on integrated control.E347No 24 Volt output on Y1 of integrated control with non-communicating outdoor unit (Y1…E348No 24 Volt output on Y2 of integrated control with non-communicating outdoor unit (Y2…E349No 24 Volts between R & O on integrated control with non-communicating outdoor unit (dual…E370Interlock switch sensed open for 2 minutes.E400LSOME401LSOME402LSOME403LSOME404LSOME405LSOME406LSOME407LSOME408LSOME409LSOMFast Flash (RAM)Normal operation with call for heat (RAM control).HeartbeatNormal operationLED Flashing 1/2 sec on 1/2 sec offLockout or Restricted Lockout condition on R7184B burner control (-5 units only).LED Flashing 2 sec on 2 sec offRecycle mode on R7184B burner controlLED OnFlame sensed by cad cell (R7184B burner control, -5 units only).LED Slow FlashControl retry periodLED Steady OnNormal operation of the G776 ignition control.LED-OFFControl failure or power failure or hard lockout (G776 ignition control, -1 and -2…LED-SLOW_FLASH_1ON_5OFFControl retry periodLED-STEADY_ONNormal operation (G776 ignition control, -1 and -2 models).LED#1 OFF / LED#2 Slow FlashPressure switch open or has opened 5 times during a single call for heat; OR blocked…LED1 ALT FAST FLASH / LED2 ALT FAST FLASHDuring ignitor warm-upLED1 ALT SLOW FLASH / LED2 ALT SLOW FLASHWatchguardLED1 Alternating Fast Flash / LED2 Alternating Fast FlashImproper main ground (controls 10M93, 57L84 during ignitor warm up only; controls 78M47 &…LED1 ALTERNATING SLOW FLASH / LED2 ALTERNATING SLOW FLASHWatchguardLED1 FAST FLASH / LED2 FAST FLASHNormal operationLED1 Fast Flash / LED2 Fast Flash (Simultaneous)Normal operationLED1 FAST FLASH / LED2 SLOW FLASHMain power polarity reversed or improper main groundLED1 OFF / LED2 ONRollout switch open or low voltage pin connector improperly attached.LED1 ON / LED2 ONCircuit board failure or control wired incorrectlyLED1 ON / LED2 SLOW FLASHFlame sensed without gas valve energized, or rollout switch open, or low voltage pin…LED1 SLOW FLASH / LED2 FAST FLASHLow flame signalLED1 SLOW FLASH / LED2 OFFPrimary or secondary limit switch openLED1 SLOW FLASH / LED2 SLOW FLASHPower onLED1 Slow Flash / LED2 Slow Flash (Simultaneous)Power onLED1-ALT_FAST_FLASH/LED2-ALT_FAST_FLASHImproper main ground or line voltage below 75 volts; OR broken ignitor; OR open ignitor…LED1-ALT_SLOW_FLASH/LED2-ALT_SLOW_FLASHWatchguardLED1-FAST_FLASH/LED2-FAST_FLASHNormal operationLED1-FAST_FLASH/LED2-SLOW_FLASHMain power polarity reversedLED1-OFF/LED2-SLOW_FLASHPressure switch open or has opened 5 times during a single call for heat; OR blocked…LED1-ON/LED2-SLOW_FLASHRollout switch open OR 9-pin connector improperly attached.LED1-SLOW FLASH / LED2-ONPrimary or secondary limit open. Units with board 12L42LED1-SLOW_FLASH/LED2-FAST_FLASHLow flame signalLED1-SLOW_FLASH/LED2-OFFFlame sensed without gas valve energized.LED1-SLOW_FLASH/LED2-ONPrimary or secondary limit open. Units with board 63K8901 or 24L85LED1-SLOW_FLASH/LED2-SLOW_FLASHPower onLED1: ON / LED2: OFFFlame sensed without gas valve energized (duplicate indication with rollout/connector…LED1: Simultaneous Fast Flash / LED2: Simultaneous Fast FlashNormal operationLED1: Simultaneous Slow Flash / LED2: Simultaneous Slow FlashPower onOffNo power to control or board fault detected.OnBoard fault detected.PulsePower onSIMULTANEOUS FAST FLASHNormal operationSIMULTANEOUS SLOW FLASHPower onSlow Flash (RAM)Normal operation, no call for heat (RAM control).Steady ON (RAM)Control board failure (RAM control).
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