The error codes on your Lennox furnace are not a threat. This guide will show you how to use them to fix the furnace.
Why Is My Lennox Furnace Showing Different Error Codes?
Error codes in Lennox furnaces correspond to particular malfunctions. The manual will tell you what each error code means. But if the furnace is using flashing lights to convey the error codes, you can blame one or more of the following:
- The lights will blink slowly because the furnace is heating as expected. You may also observe flashing because the system is calling for heat.
- A furnace with fast and slow blinking LEDs is dealing with a low flame signal.
- The flame rollout switch is defective, which is a problem because this component protects you from fires and CO poisoning.
- You have a wiring fault that has inverted the power polarity.
- If the lights are blinking and you can’t detect any heat in your home, the blower motor is not working as expected or has refused to start.
- Erratic blinking can signify a defective motherboard or loose and frayed connections.
- Does the furnace have power? Is the voltage correct? Did you trip the breaker? Some furnaces flash their LEDs and display error codes because you have a power or voltage issue.
Lennox Furnace Error Codes And Troubleshooting Tips
Error Code e227 Meaning
- You have a defective thermocouple. The sensor activates the heat when the heating coil temperature crosses a specific threshold. The furnace can’t operate when the thermocouple is broken.
- Ice has blocked a vent.
- A condensate drain pipe is clogged.
How To Fix It?
- Replace the thermocouple. You should hire a technician to perform this task if the sensor is inside the furnace. Sometimes, the thermocouple is at the back. You don’t want to tamper with a furnace unless you have the relevant experience.
- Remove blockages from the pipes and vents.
Error Code e270 Meaning
- The Lennox furnace has entered Watchguard mode because the ignitor has tried and failed to turn the flame on. You may observe a flashing red LED.
- Communication error between the control board and gas valve.
- The blower is shorting.
How To Fix It?
- Ask a technician to replace the defective ignitor, but only after checking other feasible culprits, which include the air filter, flame sensor current, gas flow, blocked hoses, etc. You don’t want to spend $400 to replace the ignitor when the problem lies elsewhere.
- Fix communication errors by identifying and resolving bad connections and frayed wiring.
- Resolve shorting by identifying and fixing loose connections.
- Make sure the furnace is properly grounded.
- Replace a faulty blower assembly.
Error Code e250
- Limit switch circuit open.
- Faulty control board.
How To Fix It?
- Clear obstructions from the vents to prevent overheating.
- Clean dirty filters. Replace the filter where necessary.
- Get a new high-limit switch.
- Perform a reset.
- Replace the control board.
Error Code e223
- Open low-pressure switch. The furnace won’t generate heat.
- You have blocked vents.
- The hose is cracked.
- Defective inducer.
- Faulty circuit board.
How To Fix It?
- Replace a damaged pressure switch. It may cost you as much as $350.
- Replace a defective inducer.
- Get a new circuit board.
Error Code e229
- The low-fire pressure switch is not working (not closing), causing the furnace to ignite at high speed.
- Blocked condensate drain.
- Blocked pressure switch tube.
- Loose wiring.
- Overheating Motor.
How To Fix It?
- Replace the low-fire pressure switch. But first, test the tubing and switch with a manometer. If you’re lucky, water in the secondary heat exchanger is causing all your problems.
- Look for water in the drain system and inducer assembly just to be on the safe side.
- Disconnect and reconnect the wires. Make sure all the connections are firm.
- Clear the drain.
Error Code e200 Meaning
- Open rollout limit switch.
- Obstructed vent pipes.
- Unstable flame.
- Poorly installed vent cap.
- Dirty heat exchanger.
- Defective vent fan.
How To Fix It?
- Reset the rollout limit switch.
- Remove any debris obstructing the flu and exhaust pipes.
- Fix or replace the vent fan.
- If you installed the furnace yourself, ask a professional to look over your work. They can fix poorly installed vent caps and misaligned ductwork. They will also find any pests obstructing the exhaust vent. You can trust the technician to search for debris and rust on the heat exchanger.
- Clean the flame sensor.
Error Code e201
- The Lennox furnace won’t turn on because it has failed to communicate with the blower motor.
- A blackout or brownout caused a glitch or malfunction.
How To Fix It?
- Turn the breakers off and on to fix communication issues between the system and the blower.
- Repair or replace the blower motor, but only after using an ECM motor test to identify the problem (The control module or the board).
- Detached wiring can prevent the blower motor from getting power. Check all the connections.
- Look for and remove moisture from the system component control.
- Replace a defective control board.
Error Code e228
- The system has refused to run because it can’t correct the pressure switch. This is for your safety.
How To Fix It?
- Replace a broken pressure switch. The switch will click a few times before the furnace shuts down, showing that the pressure switch has a fault. Additional warning signs include a flashing red light.
- Make sure the exhaust pipe and intake are clear and properly sloped.
- Identify and resolve loose wires and connections, especially at the pressure transducer.
Error Code e311
- You have an airflow problem. Check the vents for blockages. You should also inspect the filter for clogging.
- Something is blocking the blower.
How To Fix It?
- Clear the blower of obstructions.
- Clean a dirty filter and replace it where necessary.
- Inspect and clean the supply and return ducts.
- Check the motor bearings. Do they have a play? Do you need to secure or replace them?
Error Code e312
- The blower is running slower than expected because of reduced airflow. This protects the motor. But as a result, you get less heat from the furnace. This happens when the filter is dirty.
How To Fix It?
- Clean the air filter. Replace it if the component is beyond repair.
- Ask a professional to inspect the ductwork. They can fix defects and remove obstructions.
- Make sure the dampers are open.
- Replace the motor if the bearings are bad.
Error Code a475
A475 is not an error code. It is associated with airflow or air movement. (475cfm).
A475 shouldn’t concern you unless the furnace stops working whenever these figures appear. Turning the furnace off and on can eliminate the issue, but the system may stop working again after a while once A475 reappears, proving that you have a bigger problem.
You need a technician to troubleshoot the device from top to bottom, checking everything from the heat exchanger to the inducer. If you’re lucky, cleaning the flame sensor will solve the problem.
Try resetting the furnace. The process involves finding the circuit breaker and switching it to the off position before locating and using the Lennox limit switch. Resets won’t solve a tangible hardware defect. Use your warranty to get cheap or free repairs and replacements. Let the manufacturer’s technicians figure out what went wrong.
Error Code a450 Meaning
Notice that this error code starts with ‘A’ instead of ‘E,’ proving that it isn’t actually an error code. It merely reveals the cfms of the blower. In other words, your system doesn’t have an error. If it did, you would observe a proper error code.
You should only panic when the furnace stops performing as expected once you see A450. For instance, if the system is working but you can’t detect any heat.
Error Code a444 Meaning
A444 is not an error code. It will scare some people because the figures are occasionally accompanied by a flashing red light, which people associate with trouble. A444 is showing you the cfms of the air in the furnace.
444cfms is slow, but it won’t tell you anything about the malfunction in your furnace. Look for an actual error code. They begin with the letter E, not A.
Take some basic steps to resolve the symptoms you’ve observed. That includes resetting the furnace, cleaning or replacing a dirty filter, replacing the batteries in the thermostat, buying a new thermostat, cleaning clogged ducts, pipes, and vents, etc.
Troubleshooting a Lennox furnace is very difficult when you don’t see any error codes. The layperson is unlikely to identify the source of the malfunction. You are better off hiring a professional.
Error Code a600
If A600 is all you can see, you’re out of luck. A600 won’t help you troubleshoot the furnace because it simply refers to the blower speed. Error codes start with the letter E. Look for a genuine error code.
You don’t have to fix A600. This is the blower speed. It isn’t a problem or a sign of trouble. You should only take action once you notice an actual error code or if the furnace starts to malfunction.
Error Code A608
A608 is concerned with air movement.
Consider yourself lucky if A608 is the only error code you can see. This is because A608 is not an error code. You don’t have to eliminate these figures. They are trying to convey the blower speed to you.
Error Code a875
A875 refers to 875crms of air.
You don’t have to fix A875. It isn’t an error code. Numbers that are preceded by ‘A’ are concerned with air movement. Look for numbers that start with ‘E.’ All error codes start with ‘E.’ Check the manual to confirm that A875 isn’t an error code.
You can ignore A875 unless the furnace has manifested troubling symptoms. But even then, those troublesome symptoms have nothing to do with A875.
