Fuel Fired Heater Performance
The fuel-fired auxiliary heater is operating but not delivering the expected heat output within the calibrated time — flame sensor reports weak combustion, exhaust temperature does not rise, or coolant heating rate is below threshold.
Affected components
- Fuel fired heater
- Heater flame sensor
- Heater combustion chamber
Common causes
- High likelihood: Combustion chamber sooted from short cycles
- Medium likelihood: Flame sensor degraded
Related codes
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.