Enter the code your furnace, air handler, heat pump or thermostat is showing. See what it means, what usually causes it and what to check first, across 388 codes from 20+ brands.
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Codes vary between board revisions, so check the wiring diagram on your unit's access panel first. Still stuck? Talk to our tech support team.
Every code in the lookup, grouped by the control board that shows it. Brands that share a board are listed together, so a Bryant owner reads the Carrier list and a Tempstar owner reads the ICP list.
Goodman, Amana & Daikin LED flash codes
Goodman, Amana and Daikin gas furnaces report faults on a red LED on the control board, behind the blower compartment door. Count the flashes between pauses: the count is the code. A light that stays on, stays off or flashes without a pause is a code of its own. Four flashes is an open high limit, which is an airflow fault in most cases. 20 codes.
1 flashFlame failure / lockout from excessive ignition retriesAmana · Gas furnacecritical
The furnace could not establish or hold flame and has locked out.
What to check
- Clean the flame sensor and check microamps.
- Confirm gas supply and inlet pressure.
1 flashIgnition failure - retries exceeded / flame failureGoodman · Gas furnacecritical
The furnace tried to light and could not prove flame, so it has locked out.
What to check
- Clean the flame sensor with fine steel wool.
- Check the igniter for continuity and cracks.
- Confirm the gas is on and inlet pressure is correct.
2 flashesDraft inducer not operating, or pressure switch circuit closedAmana · Gas furnacecritical
Either the inducer is not running, or the pressure switch is closed when it should be open.
What to check
- Verify the inducer runs when called.
- Check the vent and condensate drain for blockage.
- Confirm the pressure switch opens with the inducer off.
2 flashesPressure switch stuck closedGoodman · Gas furnacecritical
The pressure switch is closed when the inducer is off, so the control will not start a cycle.
What to check
- Disconnect the hose and confirm the switch opens.
- Check the switch wiring for a short.
- Verify the inducer runs when called.
3 flashesOpen pressure switchAmana · Gas furnacecritical
The pressure switch is not closing when the inducer runs.
What to check
- Check the hose routing and clear any blockage.
- Replace the switch if it will not close with good vacuum.
3 flashesPressure switch stuck openGoodman · Gas furnacecritical
The pressure switch will not close when the inducer runs.
What to check
- Check the hose for blockage, water and correct routing.
- Inspect the vent and condensate drain.
- Verify inducer performance.
4 flashesPressure error / high limit errorAmana · Gas furnacecriticalmotor
A pressure or high limit fault, usually caused by restricted airflow.
What to check
- Replace the filter and clear the drain tubes.
- Confirm the blower reaches full speed and check its amp draw.
- Clean the blower wheel.
4 flashesOpen high limitGoodman · Gas furnacecriticalmotor
The high limit switch has opened, which is nearly always an airflow problem.
What to check
- Replace the filter and open all registers.
- Confirm the blower starts and reaches full speed - check amp draw and the run capacitor.
- Clean the blower wheel and coil.
- Measure temperature rise against the rating plate.
5 flashesFlame sensed without a call for heatAmana · Gas furnacecritical
Flame is present when there should be none.
What to check
- Shut off the gas and check whether the code clears.
- Replace a slow-closing or leaking valve.
5 flashesFlame sensed with gas valve offGoodman · Gas furnacecritical
The control sees flame when there is no call for heat and the valve should be closed.
What to check
- Shut the gas off and see whether the code clears.
- Replace a passing gas valve - do not leave the furnace running.
6 flashesOpen rollout switchGoodman · Gas furnacecritical
The flame rollout switch has tripped, meaning flame or hot gas escaped the burner compartment. Serious safety trip.
What to check
- Find and correct the cause before resetting.
- Inspect the heat exchanger, burners and vent.
- Confirm the inducer is running properly.
7 flashesFaulty flame sensorAmana · Gas furnacewarning
The flame sensor is not reading correctly.
What to check
- Clean the sensor and confirm its position in the flame.
- Check microamps against specification.
7 flashesLow flame senseGoodman · Gas furnacewarning
The flame signal is weak. The furnace runs but will start dropping out.
What to check
- Clean the flame sensor and check microamps.
- Verify the ground and gas pressure.
8 flashesIgniter errorGoodman · Gas furnacecritical
The igniter circuit is faulty, so the furnace cannot light.
What to check
- Measure igniter resistance and check the connector is seated.
9 flashesOpen pressure switch with induced draft blower onGoodman · Gas furnacecritical
The pressure switch is open while the inducer is running.
What to check
- Inspect the hose for cracks, water and correct routing.
- Check the vent for blockage.
Constant flashingReversed polarityAmana · Gas furnacecritical
Line and neutral are reversed at the furnace.
What to check
- Correct the line and neutral wiring and re-test.
Constant red lightNo signal from thermostatAmana · Gas furnaceinfo
The control has power but no heat call.
What to check
- Check thermostat settings and wiring.
Continuous flashingReversed polarityGoodman · Gas furnacecritical
Line and neutral are reversed at the furnace. The control needs correct polarity for flame sensing.
What to check
- Correct the line and neutral wiring.
- Verify with a receptacle tester or by measuring hot-to-ground and neutral-to-ground.
Light offControl failureGoodman · Gas furnacecritical
No light at all means the control has no power or has failed.
What to check
- Check the breaker, furnace switch and door switch.
- Check the low-voltage fuse on the board.
- Verify 24VAC at the control.
Light onNo signal from thermostatGoodman · Gas furnaceinfo
The control has power but is not receiving a call from the thermostat.
What to check
- Confirm the thermostat is set to heat and calling.
- Check thermostat wiring at both ends.
Replacement motors: Goodman blower motors · Amana blower motors · Daikin blower motors
Carrier Infinity & Bryant Evolution system codes
Infinity and Evolution systems are communicating: the furnace or fan coil, the outdoor unit and the wall control share one data line, and the wall control shows the fault number with a short description. The same number can mean different things on the indoor unit, the outdoor unit and the zoning control, so check which component the alert names. Codes 41, 44 and 15 are the blower. 130 codes, all searchable in the lookup above.
- 13 Limit switch lockout
- 15 Blower lockout
- 33 Limit fault / lost inverter communications
- 41 Blower motor fault
- 44 Cannot communicate with blower
- 161 Excess static pressure stage down
- 194 Possible frozen coil
- 210 Excessive static pressure encountered
Replacement motors: Carrier blower motors · Bryant blower motors
Carrier, Bryant & Payne 58-series LED status codes
Non-communicating Carrier, Bryant and Payne gas furnaces flash a two-digit status code on the control board LED: short flashes are the first digit and long flashes the second, so three short and three long is 33. The board keeps the last code until power is cut or 48 hours after the fault clears. 14 codes.
Every code with its fix, step by step: Carrier furnace and AC error codes explained
11No previous codeCarrier · Gas furnaceinfo
The control has no stored fault. Stored codes are cleared when power is interrupted, or 48 hours after a fault clears.
What to check
- Nothing to diagnose - this is the normal 'all clear' code.
12Blower on after power upCarrier · Gas furnaceinfo
Power was restored while a heat call was active, so the blower ran for 90 seconds.
What to check
- No action needed unless power is dropping out repeatedly.
13Limit or flame rollout switch lockoutCarrier · Gas furnacecriticalmotor
The furnace has locked out after repeated limit or rollout trips. It auto-resets after about three hours; a tripped rollout switch must be reset by hand.
What to check
- Replace the filter and check for closed dampers.
- Confirm the blower starts and reaches full speed; check amp draw and the run capacitor.
- Check the blower wheel is tight and clean.
- Reset the rollout switch or replace the fuse link, then find the root cause.
14Ignition lockoutCarrier · Gas furnacecritical
Four failed ignition attempts have locked the furnace out. It auto-resets after about three hours. See code 34 for the underlying cause.
What to check
- Work through the code 34 checks - this code is just the lockout that follows them.
21Gas heating lockoutCarrier · Gas furnacecritical
The control has locked gas heating out and will not reset itself - power must be cycled.
What to check
- Check gas valve wiring; if correct, replace the control board.
22Abnormal flame-proving signalCarrier · Gas furnacewarning
Flame was detected while the gas valve was de-energised. The inducer keeps running until this clears.
What to check
- Shut off the gas and see if the code clears. Replace a passing valve - do not leave it in service.
23Pressure switch did not openCarrier · Gas furnacewarning
The pressure switch was already closed with the inducer off.
What to check
- Check the hoses for blockage and confirm the switch opens with the inducer off.
24Secondary voltage fuse is openCarrier · Gas furnacecritical
The 24VAC fuse has blown due to a short in the low-voltage wiring.
What to check
- Disconnect the thermostat wiring, replace the fuse, and reconnect circuits one at a time to find the short.
31High-heat pressure switch or relay did not close or reopenedCarrier · Gas furnacewarning
The high-heat pressure switch never closed, or opened during high fire.
What to check
- Work through the code 32 checks as well - the causes overlap.
32Low-heat pressure, draft safeguard or aux limit switch did not close or reopenedCarrier · Gas furnacewarning
The low-heat pressure switch, draft safeguard or auxiliary limit did not close. If it stays open five minutes, the inducer shuts off for 15 minutes before retrying.
What to check
- Inspect the vent for blockage, correct length and proper termination.
- Measure inducer voltage (115VAC) and amp draw.
- Check the blower motor and run capacitor - a weak blower shows up here too.
- Check pressure hoses for water or kinks.
33Limit or flame rollout switch is openCarrier · Gas furnacewarningmotor
The high limit or flame rollout switch is currently open. If it stays open more than three minutes the code becomes a 13 lockout. Rollout switches need a manual reset.
What to check
- Replace the filter and check duct restrictions.
- Verify the blower reaches full speed - check the motor and run capacitor.
- Check the blower wheel is tight on the shaft.
- Manually reset the rollout switch or replace an open fuse link.
34Ignition proving failureCarrier · Gas furnacewarning
Flame was not proved, or was lost after the trial for ignition. The control retries three more times before locking out with code 14.
What to check
- Clean the flame sensor with fine steel wool.
- Confirm at least 0.5 microamps DC flame signal (4.0-6.0 typical on high heat).
- Make sure the green wire is bonded to the furnace sheet metal and the sensor is not grounded.
- Check the igniter and inlet gas pressure.
43Low-heat pressure, draft safeguard or auxiliary limit switch open while high-heat pressure switch is closedCarrier · Gas furnacewarning
An impossible switch combination - the low-heat side is open while the high-heat side is closed.
What to check
- Verify each hose is on the correct switch port, then work through codes 32 and 33.
45Replace controlCarrier · Gas furnacecritical
The control board has detected an internal failure and needs to be replaced.
What to check
- Cycle power once to confirm, then replace the control board.
Replacement motors: Carrier blower motors · Bryant blower motors · Payne blower motors
Trane & American Standard LED blink codes
Trane and American Standard gas furnaces blink a red LED on the control board. Count the blinks: two is a flame failure lockout, three a pressure switch problem and four an over-temperature limit, which traces back to airflow in almost every case. A light that stays on, stays off or blinks without a pause is read differently from a counted code. 12 codes.
2 blinksFlame failure - retries exceededTrane · Gas furnacecritical
The furnace lost or never established flame after its retries, so it has locked out. Often reported as the furnace blowing cold air.
What to check
- Clean the flame sensor and check microamps.
- Verify gas supply and inlet pressure.
3 blinksPressure switch problemTrane · Gas furnacecritical
The pressure switch is not in the state the control expects.
What to check
- Check the vent and condensate drain.
- Inspect the pressure hose for water, cracks and blockage.
- Verify inducer operation.
4 blinksTemperature switch problem / over temperature limitTrane · Gas furnacecriticalmotor
The limit switch has opened - an airflow problem in almost every case.
What to check
- Replace the filter and open all registers.
- Confirm the blower reaches full speed and check amp draw.
- Clean the blower wheel and inspect the secondary heat exchanger.
- Measure temperature rise against the rating plate.
5 blinksFlame sensed when no flame should be presentTrane · Gas furnacecritical
The control detects flame outside the normal sequence.
What to check
- Shut off the gas and see whether the code clears.
- Replace a passing gas valve.
6 blinks115VAC reversed polarity or poor groundingTrane · Gas furnacecritical
Line voltage polarity is reversed, or the furnace has a poor ground. Flame sensing depends on both being correct.
What to check
- Correct the line and neutral wiring.
- Clean and re-terminate the ground to bare metal on the chassis.
7 blinksGas valve circuit errorTrane · Gas furnacecritical
There is a fault in the gas valve circuit.
What to check
- Check for 24VAC at the valve during a heat call and measure the coil resistance.
8 blinksLow flame sense signalTrane · Gas furnacewarning
The flame signal is weak.
What to check
- Clean the flame sensor and check microamps.
- Verify gas pressure and grounding.
9 blinksCheck igniterTrane · Gas furnacecritical
The control has flagged the igniter circuit.
What to check
- Measure igniter resistance and check the connector.
Constant fast blinkingNormal operationTrane · Gas furnaceinfo
The furnace is functioning normally.
What to check
- Nothing to do.
Constant slow blinkingNormal operationTrane · Gas furnaceinfo
The furnace is functioning normally.
What to check
- Nothing to do.
Red light constant offCheck powerTrane · Gas furnacecritical
No power reaching the control.
What to check
- Check the breaker, furnace switch, door switch and control fuse.
Red light constant onControl failureTrane · Gas furnacecritical
The control board has failed.
What to check
- Replace the control board.
Replacement motors: Trane blower motors · American Standard blower motors
Rheem & Ruud seven-segment codes (R96V and modulating)
Rheem and Ruud modulating furnaces such as the R96V show a two-character code on a seven-segment display on the control board. A one-hour soft lockout shows 10 alternating with the code that caused it. Codes 60 and 61 are blower faults (61 means the motor cannot run), and d6 flags a horsepower conflict between the motor and the model data. 19 codes.
10One-hour lockout (soft lockout)Rheem · Gas furnacecritical
The control has locked gas heating out for one hour. It is always shown alternating with a second code that tells you why - look for the other code on the display.
What to check
- Read the code alternating with 10 - that is the real fault.
- Note: a dead blower lockout repeats up to four times in one heat call, then becomes a hard lockout needing a manual power reset.
11Failed ignitionRheem · Gas furnacewarning
The furnace failed to light on this attempt. Up to three failures is not critical; after four consecutive failures the control enters a one-hour lockout and shows 11 alternating with 10.
What to check
- Check gas supply and inlet pressure.
- Clean the flame sensor and check microamps.
- Measure igniter resistance and inspect for cracks.
12Low flame senseRheem · Gas furnacewarning
The flame signal is weaker than it should be. The furnace still runs but will start dropping out if this is left alone.
What to check
- Clean the flame sensor with fine steel wool.
- Verify the ground connection to the furnace chassis.
- Check inlet and manifold gas pressure.
13Flame lost after establishedRheem · Gas furnacewarning
Flame was proved and then went out during the heating cycle. After five losses in a row the control enters a one-hour lockout showing 13 alternating with 10.
What to check
- Clean the sensor and re-check microamps while running.
- Measure gas pressure during operation, not just at rest.
- Check the vent and intake for restriction.
14Flame present with gas valve off (unexpected flame)Rheem · Gas furnacecritical
The control sees flame when the gas valve should be closed. This causes a one-hour lockout showing 14 alternating with 10.
What to check
- Shut off the gas and see whether the code clears - if it does, the valve is passing gas.
- Replace a leaking gas valve. Do not leave the furnace in service.
30Open fuseRheem · Gas furnacecritical
The low-voltage fuse on the furnace control has opened, so there is no 24V control power.
What to check
- Disconnect the thermostat wiring and fit a new fuse. If it holds, the short is external.
- Check accessory wiring for humidifiers and air cleaners.
33Over-temperature switch (rollout) openRheem · Gas furnacecritical
A rollout or over-temperature switch has opened, meaning hot gas or flame escaped the burner area. This is a serious safety trip.
What to check
- Find and correct the cause before resetting anything.
- Inspect the heat exchanger, burners and vent thoroughly.
- Confirm the inducer runs at the correct speed.
44Low pressure switch closed, inducer offRheem · Gas furnacecritical
The low pressure switch is closed with the inducer off. The control tests for this before every cycle because a closed switch here means the safety is not working.
What to check
- Disconnect the hose and confirm the switch opens.
- Remove any field bypass and find out why it was fitted.
- Check the vent for proper termination.
45Low pressure switch open, inducer on high speedRheem · Gas furnacecritical
The low pressure switch will not close with the inducer running at high speed.
What to check
- Check the vent system for blockage and correct termination.
- Compare vent length and elbows against the installation instructions.
- Check inducer operation and wiring.
- Replace cracked or blocked hoses.
46Low pressure switch open, inducer on low speedRheem · Gas furnacecritical
The low pressure switch will not close with the inducer at low speed. Often the furnace will still run on high fire.
What to check
- Check the vent and hoses first.
- Verify inducer performance at low speed.
55High pressure switch closed, inducer offRheem · Gas furnacecritical
The high pressure switch is closed with the inducer off, which should never happen.
What to check
- Replace the high pressure switch if it does not open with the hose off.
- Remove any bypass and correct the reason it was fitted.
- Check venting and terminations.
57High pressure switch open, inducer on high speedRheem · Gas furnacecritical
The high pressure switch is open with the inducer at high speed. If the low pressure switch stays closed, the furnace drops to low fire and keeps running.
What to check
- Check the vent for blockage and correct termination.
- Verify vent length and elbow count against the specification sheet.
- Repair or replace the inducer and its wiring.
- Replace damaged hoses.
58Water circuit openRheem · Gas furnacecritical
The control cannot detect continuity between pins 1 and 2 of connector P4, which it uses to confirm both water sensors are present. Gas heating is blocked.
What to check
- Repair or replace the sensor wiring.
- Reseat the P4 connector.
- Refit any missing water sensor.
59Water sensedRheem · Gas furnacecritical
The control has detected water in the collector box for at least ten seconds. Gas heating is stopped; cooling still works.
What to check
- Clear the condensate drain and trap.
- Repair sensor wiring that is contacting the chassis.
- Return the sensors to their proper location in the collector box.
60Blower fault - blower can still runRheem · Gas furnacewarningmotor
The blower has hit a limit set by the manufacturer but can keep running. Everything still operates, though airflow is compromised.
What to check
- Measure total external static pressure - it is almost always too high.
- Replace or clean the filter and clean the blower wheel and coil.
- Correct restricted or undersized ductwork so static stays within the published values.
- Left uncorrected this shortens motor life and eventually becomes a code 61.
61Blower fault - motor cannot runRheem · Gas furnacecriticalmotor
The blower motor has failed critically or tripped a limit that stops it running altogether. The furnace will not operate in any mode. This is the primary Rheem blower motor failure code.
What to check
- Kill power and spin the blower wheel by hand - check for drag, bearing noise or a loose wheel.
- Inspect and test the PFC choke; a failed choke will stop the motor with an otherwise good motor.
- Inspect the motor and PFC wiring and connectors for damage.
- Confirm the wheel is properly secured on the shaft.
- Replace the memory card if the model data is corrupt.
- If the motor is hot, it has thermally tripped - find the restriction, then replace the motor if it will not recover.
- Note: after the main limit opens for more than 150 seconds four times in one heat call, the control enters a hard lockout needing a manual power reset.
d1No model dataRheem · Gas furnacecritical
The furnace has no model data, so it does not know the blower speed and torque curve it needs. Nothing will run - not even a thermostat call.
What to check
- Fit the correct memory card into connector P6 on the furnace control.
- If a control was just replaced, the original card must be moved to the new board.
- Cycle furnace power off and back on after fitting the card, or the data will not be read.
- Order a replacement card by furnace model and serial if the original is lost.
d4No valid model data on memory cardRheem · Gas furnacewarning
The memory card is blank, corrupt or missing, but a good copy of the model data is still stored in the furnace control. The furnace should still run normally.
What to check
- Fit the correct original or replacement memory card.
- Never use a memory card from another furnace or from a condenser or air handler - wrong blower data can damage the heat exchanger.
d6Horsepower conflict on memory cardRheem · Gas furnacewarningmotor
The horsepower the blower motor reports does not match the horsepower stored on the memory card, although the control's own copy does match the motor. The furnace should still operate.
What to check
- Read the horsepower on the motor nameplate and compare with the furnace rating plate.
- If a replacement motor was fitted recently, this code usually means it is the wrong horsepower.
- Fit the correct motor or the correct model data card - do not mix cards between units.
Replacement motors: Rheem blower motors · Ruud blower motors
Lennox iComfort & Comfort Sync alert codes
Lennox communicating systems show a numbered alert on the iComfort or Comfort Sync thermostat, together with the unit that raised it. The 200 range comes from the furnace or air handler, including 201 (lost communication with the indoor blower motor), 202 (motor size mismatch) and 292 (blower will not start); the 400 range covers the outdoor unit and compressor. Armstrong Air, AirEase, Concord and Ducane communicating equipment uses the same list. 143 codes, all searchable in the lookup above.
- 201 Lost communication with the indoor blower motor
- 202 Unit size code and blower motor size do not match
- 203 Unit size code has not been selected
- 250 Primary limit switch open
- 252 Discharge air temperature high
- 274 Limit switch open more than three minutes
- 291 Heating airflow below the minimum required level
- 292 Indoor blower motor will not start
- 295 Indoor blower motor overheating
- 311 Heat firing rate reduced to match available airflow (cutback mode)
- 312 Blower cannot provide requested CFM due to high static pressure
Replacement motors: Lennox blower motors
Heil, Tempstar, Comfortmaker & Arcoaire LED flash codes
Furnaces built by ICP and sold as Heil, Tempstar, Comfortmaker, Arcoaire and KeepRite flash an LED on the control board, and the count is the code. Two and three flashes are pressure switch faults, four is an open high limit and six points at the inducer motor, not the blower. 8 codes.
1 flashIgnition failureArcoaire · Gas furnacecritical
The furnace attempted to light and failed.
What to check
- Clean the flame sensor and check the igniter.
- Confirm gas supply and inlet pressure.
2 flashesPressure switch stuck openArcoaire · Gas furnacecritical
The pressure switch is not closing when the inducer runs.
What to check
- Check the tubing and vent for blockage.
- Verify inducer operation and amp draw.
3 flashesPressure switch stuck closedArcoaire · Gas furnacecritical
The pressure switch is closed with the inducer off.
What to check
- Confirm the switch opens with the hose off.
- Remove any field jumper.
4 flashesHigh limit switch openArcoaire · Gas furnacecriticalmotor
The high limit has opened, which points to restricted airflow.
What to check
- Replace the filter and open all registers.
- Confirm the blower reaches full speed and check amp draw and the run capacitor.
- Clean the blower wheel.
5 flashesRollout switch trippedArcoaire · Gas furnacecritical
The flame rollout switch has tripped - flame or hot gas escaped the burner area. Serious safety trip.
What to check
- Find and correct the cause before resetting.
- Inspect the heat exchanger, burners and vent.
6 flashesFaulty inducer motorArcoaire · Gas furnacecritical
The draft inducer motor is not performing as required.
What to check
- Check the inducer for free rotation and unusual noise.
- Measure its amp draw against specification.
- Inspect the vent for blockage.
7 flashesFaulty gas valveArcoaire · Gas furnacecritical
The gas valve or its circuit is at fault.
What to check
- Check for 24VAC at the valve during a heat call and measure the coil resistance.
8 flashesInternal control board failureArcoaire · Gas furnacecritical
The control board has detected an internal failure.
What to check
- Cycle power once, then replace the control board if the code returns.
Replacement motors: Heil blower motors · Tempstar blower motors · Comfortmaker blower motors
York, Coleman & Luxaire split system codes
These letter-and-number codes appear on the indoor unit display or the central controller of York, Coleman and Luxaire ducted split and central air systems. E and F codes are unit faults, P codes are protection trips and H codes come from the central controller. York gas furnaces use LED flash codes, which are not in this list yet. 34 codes, all searchable in the lookup above.
Replacement motors: York blower motors · Coleman blower motors
Ducane & Armstrong Air red LED flash codes
Ducane and Armstrong Air furnaces, built by Lennox, flash a red LED on the ignition control. Count the flashes: two is a pressure switch closed with the inducer off, three a low-fire pressure, rollout or limit switch open, and four an open high limit. 8 codes.
1 flashFlame present with gas valve offDucane · Gas furnacecritical
Flame is detected when the gas valve should be closed.
What to check
- Clean the flame sensor rod.
- Replace a slow-closing or leaking gas valve.
2 flashesPressure switch closed with inducer offDucane · Gas furnacecritical
The pressure switch is closed when the inducer is not running.
What to check
- Confirm the switch opens with the hose off.
- Verify the inducer runs when called.
3 flashesLow fire pressure, rollout or limit switch openDucane · Gas furnacecritical
A low fire pressure, rollout or limit switch is open.
What to check
- Inspect the heat exchanger and vent.
- Reset the rollout switch only after correcting the cause.
4 flashesHigh limit switch openDucane · Gas furnacecriticalmotor
The high limit has opened - an airflow problem.
What to check
- Replace the filter and clean the blower wheel.
- Confirm the blower reaches full speed and check amp draw.
6 flashesPressure switch cycle lockoutDucane · Gas furnacecritical
The pressure switch has cycled too many times and the control has locked out.
What to check
- Clear the vent and condensate drain, then replace the switch if needed.
7 flashesLockout - no ignitionDucane · Gas furnacecritical
The furnace has locked out because it never lit.
What to check
- Clean the flame sensor and check the igniter.
- Replace the filter.
8 flashesLockout - too many flame dropoutsDucane · Gas furnacecritical
Flame kept dropping out until the control locked out.
What to check
- Clean or replace the flame sensor.
- Check gas pressure while running.
9 flashesPolarity and phasing errorDucane · Gas furnacecritical
Line voltage polarity or phasing is wrong.
What to check
- Correct the line and neutral wiring.
Replacement motors: Lennox-built blower motors
How to read your HVAC fault code
Where do I find the error code on my furnace or heat pump?
It depends on the equipment. Most gas furnaces flash the code on an LED on the control board, behind the blower compartment door. Some modulating furnaces, such as the Rheem R96V, show it on a small seven-segment display instead. Communicating systems (Carrier Infinity, Bryant Evolution, Lennox iComfort and Comfort Sync) show the code and a short description on the wall control. Ductless and ducted split systems usually show a letter-and-number code such as E3 or F5 on the indoor unit display.
How do I read a flashing LED code?
Count the flashes between pauses. On most brands the count is the code, so four flashes is code 4. Carrier, Bryant and Payne 58-series furnaces use two digits: short flashes are the first digit and long flashes the second, so three short and three long is code 33. Codes change between board revisions, so compare against the diagram printed inside the access panel of your unit.
What does a blinking red or green light on my furnace mean?
It depends on the brand, so the color alone is not a diagnosis. On many furnaces a green LED shows normal status, while a red or amber LED that blinks in a repeating count is a fault code: count the blinks between pauses and search that count here with your brand, for example Goodman 3 flashes or Trane 4 blinks. A light that stays solid red or flashes without a pause is a separate code on Goodman, Amana and Trane boards.
How do I clear a furnace error code?
Fix the cause first, then reset. Many controls clear a lockout on their own: Rheem R96V boards lift a soft lockout after one hour, and Carrier 58-series boards reset a limit lockout after about three hours. You can also switch the power off at the furnace service switch and back on. If the same code returns, the fault is still there. Do not keep resetting flame rollout, limit or gas valve codes: have a licensed technician check the furnace.
Why does the same code mean different things on different equipment?
Because a code only means something on the board that generated it. On Carrier Infinity equipment 41 is a blower motor fault, while on another manufacturer's board the same number can point at something unrelated. On communicating systems the same number can even differ between the indoor unit, the outdoor unit and the zoning control. That is why every result here names the brand, the equipment family and the component it applies to.
Which codes point at a bad blower motor?
Codes that name the blower directly: Carrier Infinity and Bryant Evolution 41 (blower motor fault), 44 (cannot communicate with the blower) and 15 (blower lockout); Lennox 201 (lost communication with the indoor blower motor), 202 (motor size mismatch), 292 (blower will not start) and 295 (blower overheating); Rheem and Ruud 60 and 61 (blower fault, motor can or cannot run). High limit codes, such as Carrier 13 and 33, Lennox 250 and 274, and four flashes on Goodman, Amana, Trane and Arcoaire furnaces, are airflow faults: a failing blower motor is one cause, and so are a dirty filter, a dirty blower wheel and restricted ductwork. Before you order a part, run the checks in our ECM motor testing guide or the multimeter test.
My blower motor code came back after I replaced the motor. Why?
Almost always because the restriction behind it is still there. A blower motor that trips on thermal overload or hits its torque limit is usually pushing air through a dirty filter, a dirty blower wheel, a plugged coil or undersized ductwork. Replace the filter, clean the wheel and coil, and measure total external static pressure against the blower table before you fit a new motor, otherwise the new one fails the same way. On two-piece ECM motors the control module fails far more often than the motor itself, so test it separately (ECM 2.3, 2.5, 3.0 and EON guide; for one-piece motors, the X13 guide). On Lennox and Rheem equipment the horsepower of the replacement must match the original exactly, or the control throws a size-mismatch code (Lennox 202, Rheem d6). If a motor you bought from us shows a code, see what to do when a new motor shows an error code.
Is a code the same thing as a diagnosis?
No. A fault code tells you which safety or sensor the control tripped on, not which part failed. A high limit code means the furnace got too hot: that can be a dirty filter, a closed damper, a slipping blower wheel, a failing motor or a bad limit switch. Use the code to narrow down where to look, then measure. For symptom-based checks, start with our blower motor troubleshooting guide. Anything involving gas, flame rollout, a cracked heat exchanger or line voltage belongs to a licensed technician.
My code isn't listed. What now?
Fault codes vary between manufacturers, product lines and board revisions, so no single list covers everything. Check the diagram inside your unit's access panel and the manufacturer references on this page. If you still can't place it, send us the code with the model and serial number from the rating plate and we'll look it up. Not sure what equipment you have? Decode the rating plate with our HVAC serial number lookup.