Troubleshooting

Common HVAC Error Codes: Quick Reference Guide by Manufacturer

Quick reference guide to common fault codes from major HVAC manufacturers including Carrier, Trane, Lennox, and Goodman.

NT
NOLT HVAC Team
Industry Experts
Dec 22, 2025
11 min read

Carrier/Bryant Fault Codes

LED Flash Codes

FlashesMeaningAction
1 flashSystem lockout (retries exceeded)Reset power, check ignition
2 flashesPressure switch stuck closedCheck inducer, pressure switch
3 flashesPressure switch stuck openCheck venting, inducer, hose
4 flashesOpen high limitCheck airflow, filter, blower
5 flashesFlame sensed without gas valveCheck gas valve, flame sensor
6 flashes115V power reversed or no groundCheck electrical connections
7 flashesLow flame signalClean flame sensor
8 flashesIgnitor failureCheck/replace ignitor

Trane/American Standard Codes

XL/XV Series LED Codes

FlashesMeaning
1 redSystem lockout - call for heat not completed
2 redSystem lockout - recycle limit exceeded
3 redInduced draft blower fault
4 redOpen high temperature limit
5 redFlame sense without gas valve
AlternatingGas valve circuit failure
Continuous ONControl board failure
Continuous OFF24V power failure

Lennox Codes

SLP/EL Series

CodeMeaning
E225Rollout switch open
E227Limit switch open
E228Flame not sensed during trial
E250Inducer motor fault
E251Pressure switch stuck open
E270Low flame signal
E290Indoor blower motor fault

Goodman/Amana Codes

Common LED Codes

FlashesMeaning
1 flashLockout due to no ignition
2 flashesPressure switch stuck closed
3 flashesPressure switch stuck open
4 flashesLimit switch open
5 flashesFlame sensed with gas valve off
6 flashesVoltage issue
7 flashesLow flame microamps
9 flashesReversed line voltage polarity
Pro Tip: Always photograph the diagnostic label inside the furnace door. It has the specific code chart for that model, which can vary by age and series.

Parts for Any Code

NOLT stocks ignitors, flame sensors, pressure switches, and control boards for fast repairs.

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NT

NOLT HVAC Team

Industry Experts & Technical Writers

Our team of HVAC professionals, certified technicians, and industry experts share practical knowledge to help contractors and technicians excel in their work. With decades of combined experience, we're committed to providing actionable insights.