Trane fault codes

Likely causes, most common first

1. Normal operation with no heat call from the thermostat

What you can safely check yourself

• If the house is cold, check that the thermostat is set to Heat and set above room temperature
• Check thermostat batteries if it has them

Likely causes, most common first

1. Normal operation during a heating cycle

Likely causes, most common first

1. Failed integrated furnace control board

What you can safely check yourself

• Turn the furnace switch off and back on once to confirm the LED really stays solid rather than flashing a code

Likely causes, most common first

1. No line power reaching the furnace
2. Open circuit breaker or blown fuse
3. Furnace disconnect switch off
4. Blower door not fully seated, which opens the door switch

What you can safely check yourself

• Make sure the main furnace switch (usually a light-switch near the furnace or at the top of the basement stairs) is in the ON position
• Reset the circuit breaker, or replace a blown fuse
• Make sure the furnace blower door is fully closed and latched

Likely causes, most common first

1. Loss of flame or gas supply failure - the control recycled the ignition sequence and never achieved ignition, so it shut off the gas valve and locked out the system
2. Ignition failure at the burners
3. Flame sensed then repeatedly lost during the heating cycle

What you can safely check yourself

• Check that other gas appliances in the house are working, which tells you whether gas is reaching the home at all
• Reset once by cycling power: turn the system power off, then on, then off, then on again within 30 seconds at the furnace switch or thermostat

Likely causes, most common first

1. Venting problem
2. Pressure switch problem
3. Inducer problem
4. Excessive combustion pressure (wind in excess of 40 m.p.h.), vent or flue blockage
5. Condensate drain blockage from debris, improper draining, or freezing condensate (condensing models)
6. Induced draft blower failure - if pressure is not sensed, the contacts remain open and will not allow the gas valve to open

What you can safely check yourself

• Go outside and check the PVC intake and exhaust pipes for snow, ice, leaves, or a bird/insect nest blocking them
• Check the condensate drain line and trap for a clog, and make sure any condensate pump is working and not full
• Check that the vent terminations are clear after heavy wind or snow

Likely causes, most common first

1. Restricted airflow across the heat exchanger - the manual's own limit checkout deliberately trips the limit by 'blocking the return air', which is what a dirty filter or blocked returns do in service
2. Blocked vent or combustion air inlet terminations (the manual's burner-box limit reset step says 'The vent and combustion air inlet terminations should be checked for blockage')
3. Faulty limit switch

What you can safely check yourself

• Check the air filter and clean or replace it if it is dirty
• Check that supply registers and return grilles are open and not blocked by furniture or rugs
• Check the outdoor vent and combustion air intake terminations for blockage

Likely causes, most common first

1. Flame sensed when no flame should be present
2. Gas valve leaking through or slow to close
3. Faulty flame sensing circuit

What you can safely check yourself

• Turn the furnace switch off and leave it off
• If you smell gas, leave the house and call the gas utility from outside

Likely causes, most common first

1. 115 Volt AC power reversed
2. Poor grounding

What you can safely check yourself

• Note whether the code appeared right after electrical work, a new outlet, or a generator was used

Likely causes, most common first

1. Gas valve circuit error

What you can safely check yourself

• Turn the furnace switch off and leave it off until a technician has looked at it

Likely causes, most common first

1. Low flame sense signal

What you can safely check yourself

• Note whether the furnace is still heating; this code usually appears while the furnace is still running

Likely causes, most common first

1. Igniter circuit fault
2. Possible grounding problem (Line "N" to 24VAC "Common" voltage should be under 2 volts)

What you can safely check yourself

• Note whether the furnace tries to start and never lights

Likely causes, most common first

1. Loss of the IRQ or other internal failures (Internal IFC error)

What you can safely check yourself

• Turn the furnace switch off, wait a minute, and turn it back on once to see whether the code clears

Likely causes, most common first

1. Flame never sensed on repeated ignition attempts
2. No gas or interrupted gas supply
3. Failed igniter
4. Dirty or failed flame sensor

What you can safely check yourself

• Check that other gas appliances in the house work, which tells you gas is reaching the home
• Check that the manual gas shutoff at the furnace has not been left closed after service
• Reset once by turning the furnace switch off and back on

Likely causes, most common first

1. Flame sensed then lost, ten times
2. Marginal flame signal or dirty flame sensor
3. Low or unstable gas pressure
4. On the S9V2-VS, the first-stage pressure switch opening ten times during a cycle

What you can safely check yourself

• Check the air filter and replace it if dirty
• Check the outdoor intake and exhaust terminations for blockage
• Reset once by turning the furnace switch off and back on

Likely causes, most common first

1. First stage gas valve not energized when it should be
2. Gas valve or gas valve wiring fault
3. Control board output fault

Likely causes, most common first

1. Shorted pressure switch, 1st stage
2. Pressure switch contacts stuck closed
3. Wiring fault across the pressure switch

Likely causes, most common first

1. Open pressure switch, 1st stage
2. Blocked or restricted vent or combustion air piping
3. Condensate backing up in the drain or trap (condensing models)
4. Draft inducer not running or running weak
5. Pressure switch tubing disconnected or plugged

What you can safely check yourself

• Check the outdoor intake and exhaust pipes for snow, ice, leaves, or nests
• Check the condensate drain line and trap for a clog, and check that any condensate pump is working
• Check that the furnace blower door is fully closed

Likely causes, most common first

1. Shorted pressure switch, 2nd stage
2. Second-stage pressure switch contacts stuck closed

Likely causes, most common first

1. Open pressure switch, 2nd stage
2. Restricted or blocked venting
3. Draft inducer not reaching high-stage speed
4. Pressure switch tubing problem

What you can safely check yourself

• Check the outdoor intake and exhaust terminations for blockage
• Check the condensate drain and trap for a clog (condensing models)

Likely causes, most common first

1. Open limit (main thermal, rollout switch, or reverse airflow switch)
2. Restricted airflow across the heat exchanger from a dirty filter or blocked returns
3. Blocked vent or combustion air terminations
4. Flame rollout, which indicates a blocked heat exchanger or burner problem

What you can safely check yourself

• Check the air filter and clean or replace it if dirty
• Check that supply registers and return grilles are open and unblocked
• Check the outdoor intake and exhaust terminations for snow, ice, or debris

Likely causes, most common first

1. Open high limit switch
2. Restricted airflow from a dirty filter or blocked returns
3. Blower not running or running slow

What you can safely check yourself

• Check the air filter and clean or replace it if dirty
• Check that supply registers and return grilles are open and unblocked
• Make sure nothing is blocking the return air path to the furnace

Likely causes, most common first

1. Open reverse air-flow limit switch
2. Blower rotating backwards or wired incorrectly
3. Airflow problem specific to the furnace's installed orientation

What you can safely check yourself

• Check that the furnace blower door is fully closed and latched
• Check the air filter and replace it if dirty

Likely causes, most common first

1. Open roll-out limit switch
2. Blocked or cracked heat exchanger
3. Blocked vent or restricted combustion air
4. Burner or gas pressure problem

What you can safely check yourself

• Turn the furnace switch off and leave it off
• If you smell gas or see soot, leave the house and call the gas utility from outside

Likely causes, most common first

1. Flame detected, should not be present
2. Gas valve leaking through or slow to close
3. Flame sensing circuit fault

What you can safely check yourself

• Turn the furnace switch off and leave it off
• If you smell gas, leave the house and call the gas utility from outside

Likely causes, most common first

1. Voltage reversed polarity
2. Bad grounding

What you can safely check yourself

• Note whether the code appeared after electrical work or after the furnace was run on a generator

Likely causes, most common first

1. Voltage reversed polarity

What you can safely check yourself

• Note whether the code appeared right after electrical work or a new circuit was run

Likely causes, most common first

1. Bad grounding

Likely causes, most common first

1. Igniter relay fails
2. Igniter open

What you can safely check yourself

• Turn the furnace switch off and back on once to see whether the furnace attempts to light

Likely causes, most common first

1. 1st stage gas valve (MVL) is energized when it should be off
2. Gas valve relay stuck closed on the control board

What you can safely check yourself

• Turn the furnace switch off and leave it off until a technician has looked at it

Likely causes, most common first

1. Redundant relay (HLO output) energized when it should NOT be
2. Control board relay fault

Likely causes, most common first

1. Flame current is low, but still strong enough to allow operation
2. Dirty or degraded flame sensor
3. Weak or poorly positioned burner flame
4. Marginal grounding

What you can safely check yourself

• Note that the furnace is likely still heating; schedule service rather than treating it as an emergency

Likely causes, most common first

1. Open inducer limit switch or condensate pressure switch
2. Blocked condensate drain, trap, or hose
3. Frozen condensate in an outdoor-run drain line
4. Full or failed condensate pump
5. Inducer overheating

What you can safely check yourself

• Check the condensate drain line and trap for a clog and clear standing water from the drain pan area if you can reach it safely
• Check that any condensate pump is plugged in, not full, and pumping
• In freezing weather, check whether any part of the drain line runs somewhere cold enough to freeze

Likely causes, most common first

1. Inducer motor no communication response
2. Communication failure between two micro-controllers
3. Loose inducer motor harness

What you can safely check yourself

• Turn the furnace switch off and back on once to see whether the code clears

Likely causes, most common first

1. 1st stage gas valve not energized when it should be
2. 1st stage gas valve relay stuck closed
3. 2nd stage gas valve relay stuck closed
4. 2nd stage gas valve energized when it should not be
5. 2nd stage gas valve not energized when it should be

What you can safely check yourself

• Turn the furnace switch off and leave it off until a technician has looked at it

Likely causes, most common first

1. Open fuse
2. Short in the low-voltage thermostat or accessory wiring
3. Short in a control circuit component

What you can safely check yourself

• Note whether the code appeared right after a thermostat was replaced or new low-voltage wiring was run, and mention that to the technician

Likely causes, most common first

1. Blower HP or OEM ID do not match furnace
2. Wrong replacement blower motor installed
3. Wrong or missing personality module

What you can safely check yourself

• Mention to the technician whether the blower motor or control board was recently replaced

Likely causes, most common first

1. Blower motor no communication response
2. Loose or damaged motor communication harness
3. Failed blower motor control module

What you can safely check yourself

• Turn the furnace switch off and back on once to see whether the blower starts
• Make sure the blower door is fully closed and latched