Appliance diagnostic hub

Furnace error codes

Search 9 Furnace diagnostic guides across 6 brands, or choose a manufacturer to narrow the database.

Brands with Furnace guides

Diagnostic search

Search by brand, appliance, error code, symptom, likely cause, or replacement part.

9 guides found

Code 13 indicates primary limit switch opened 3 consecutive times in a single heat call, putting system into temporary auto-lockout.

Code 14 signals furnace failed to maintain flame control after 4 consecutive ignition retry attempts.

Code 31 signals that the furnace draft inducer motor ran, but the pressure switch failed to sense proper negative draft pressure.

Code 33 indicates the high-limit switch or rollout switch has tripped due to excessive heat build-up inside the furnace main heat exchanger.

Goodman E2 code alerts that the microamp flame signal current dropping below minimum required threshold during operation.

E4 indicates the main limit switch circuit opened due to excessive heat build-up inside the plenum.

Code 11 triggers on Rheem and Ruud furnaces when main flame is not established within 4 seconds of gas valve opening.

3 red light flashes on a Trane furnace board indicate the pressure switch circuit is open when it should be closed during combustion startup.

Code d3 indicates pressure switch opened during active burner operation, dropping out flame for safety.