Skip to main content
Trane Furnace Error Codes
79 error codes for Trane furnace models. Each links to the full diagnostic procedure from the service manual.
CodeDescription
1Flame sensed when no flame should be present.1 Flash (Red)Normal LitePort data transmission1 GREENStandby mode or call for cooling.1 GREEN / 1 AMBER1st stage call for heat.1 REDFlame sensed when no flame should be present.10Gas valve energized without call for heat.10 FlashCommunication fault10 REDGas valve energized without call for heat.11Primary limit has been open for more than 5 minutes, check blower.12Ignitor relay failure internal in board12 REDIgnitor relay failure internal in board2Pressure switch is stuck closed.2 FlashFlame lost or ignition failure2 GREEN / 1 AMBER2nd stage call for heat.2 REDPressure switch stuck closed.31st stage pressure switch is stuck open (not closing).3 Double2nd stage pressure switch open3 DOUBLE RED2nd stage pressure switch open; system reverts back to 1st stage heat.3 FlashPressure switch or inducer error3 GREEN / 1 AMBERW2 call present without W1.MyPros+ Max
Get the full diagnostic procedure for any Trane furnace error code.
- Step-by-step tests with expected resistance, voltage, and continuity values
- Wiring diagram references and connector pinouts
- Verified part numbers when replacement is required
Get started
$29/month · Cancel anytime · Or $9.95 3-day pass
3 RED1st stage pressure switch is open or not closing.4Open primary limit, flame roll out or reverse flow switch.4 FlashHigh temperature limit fault4 GREEN / 1 AMBERY call present without G.4 REDOpen thermal limit or open rollout.5Open roll out switch or open low voltage fuse.5 FlashFlame detect fault5 REDOpen low voltage fuse.61st stage pressure switch has opened 5 times within one cycle6 FlashLine polarity fault (voltage reverse polarity), ground fault (proper earth…6 RED1st stage pressure switch opened 5 times within one cycle7System lockout Retry7 FlashExternal gas valve circuit error7 REDSystem lockout Retry.8System lockout Recycle8 FlashLow flame sense signal8 REDSystem lockout Recycle.9Reverse polarity or poor grounding.9 FlashOpen inducer limit error9 REDReverse polarity or poor grounding.CFMB Blinking Red LEDFasco Motor Control Board (CFMB) has shut down due to overcurrent or…ERR 10Ignition means faultERR 101Y1 relay failureERR 114Bad or missing personality moduleERR 119Temperature sensor failureERR 139Communication failureERR 18Internal control failure.ERR 22Soft lockout due to flame lost or ignition retries (10 recycles or 3 ignition…ERR 26High temp limit faultERR 34Line polarity faultERR 87Flame detect faultERR 91Communication faultERR 93Gas valve faultFast FlashPersonality Module errorGreen Continuous / Red FlashingGas valve miswired or flame signal present at a call for heat.Green Fast FlashNormal operation, call for heat present.Green OFF / Red ContinuousInternal fault detected on Texas Instruments ignition control module (can occur…Green OFF / Red FlashingIgnition control module locked out on failure to establish flame signal.Green OFF / Red Flashing (during ignition try)No flame signal on try for ignition or flame signal lost during ignition try.Green Slow FlashNormal operation, no call for heat.Green/Red LEDs on continuouslyFuse open or internal control failure.None (AC VOLTS HI)AC line voltage too high.None (AC VOLTS LOW)AC line voltage too low.None (CAP MISMATCH)Compressor size does not match capacity in Personality Module.None (CHECK FUSE)24V control fuse is open.None (ID MTR ERR)Blower HP/OEM does not match Personality Module data.None (TS 1 OPEN)Temperature sensor 1 is open.None (TS 1 SHORT)Temperature sensor 1 is shorted.None (TS 2 OPEN)Temperature sensor 2 is open.None (TS 2 SHORT)Temperature sensor 2 is shorted.None (TWIN ERROR)Twinning not allowed with variable speedNone (Y1 OFF ERR)Y1 relay failureNone (Y1 ON ERR)Y1 output is ON when it should be OFF.RapidTwinning Error, incorrect 24V Phasing.RAPID GREEN / 1 AMBERLow flame sense current.Solid ONInternal control failure (ERR 18)Solid RedInternal gas valve circuit error (damaged furnace control)Solid Red (continuous reset)Continuous reset caused by an internal error (damaged furnace control).Solid STATUS (Red OFF)24VAC fuse open