P2029

Code

Generic P — Powertrain

Fuel Fired Heater Disabled

Brand: Generic

Type: P — Powertrain

Views: UK: 18 EN: 26 RU: 22

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Page language: EN

Heater control unit set to disabled by software or vehicle settings
Blown fuse or failed relay in heater power/control circuit
Open or shorted wiring/poor connector ground to heater or control unit
Low battery or supply voltage to heater controller
Safety interlock active (overtemperature, overpressure, low coolant level, door/hood switch)
Fuel supply fault to the heater (blocked line, failed pump, empty tank)

Read all stored codes and freeze frame data from heater controller and vehicle modules
Verify vehicle software/settings do not intentionally disable the heater (user menu, immobilizer, timer settings)
Check fuses and relays for heater power and control circuits
Inspect wiring and connectors for corrosion, damage or loose pins at heater and controller
Check battery and charging system voltage (engine off and cranking)
Use a scan tool to request heater on/off and watch live data for errors or interlocks

Heater enable request from BCM/remote (digital command on CAN or dedicated input)
Heater controller supply voltage (12 V system voltage)
Ground continuity at heater control and module
Relay control output and switched power to heater
Fuel pump current/voltage (heater fuel supply)
Coolant temperature and heater temperature sensor readings

Verify and record P2029 and any other stored DTCs from all control modules. Note conditions and freeze frame data.
Check owner settings and immobilizer/remote start settings that can disable the heater; enable if intentionally turned off.
Inspect fuses and relays for the heater circuit; replace any blown fuses and swap or test relays.
Visually inspect wiring, connectors and grounds at the heater and heater control unit; repair corrosion or damaged wiring.
With a scan tool, command the heater ON and observe live inputs/outputs. If the controller refuses the request, record shown interlock or reason.
Measure supply voltage at heater control connector while requesting operation. Low voltage or repeated drops indicate battery/charging or high resistance issue.
Verify fuel supply to the heater: check fuel pump operation, lines for blockage, and fuel pressure/current to the heater unit.
Check safety sensors (coolant level/temp, exhaust temp, overtemp switches) for correct readings and replace if out of spec.
If electrical inputs and sensors are good but heater still disabled, perform a bench or module self‑test per manufacturer procedures or replace the heater control unit.
After repairs, clear DTCs, perform heater request and operate through full run cycle to confirm fault not recurring; road or cold‑start verify cabin/engine preheat as applicable.