P2029 Fuel Fired Heater Disabled
OBD-II Trouble Code Technical Description
Fuel Fired Heater Disabled
What does that mean?
This diagnostic trouble code (DTC) is a generic powertrain code and applies to many OBD-II vehicles (1996-newer). That may include but is not limited to vehicles from Mercedes-Benz, Land Rover, Opel, Toyota, Volvo, Jaguar, etc. Although generic, the exact repair steps may vary depending on year, make, model and powertrain configuration.
If your vehicle has stored a code P2029, it means that the powertrain control module (PCM) has detected a malfunction in the auxiliary or fuel fired heater system that has resulted in deactivation. This type of code is applicable to vehicles with fuel fired heater systems only.
Creating cabin heat in vehicles with modern, clean-burning diesel engines can be challenging especially in geographic areas with extremely cold ambient temperatures. Due to the overall mass of the diesel engine, heating the engine enough for the thermostat to open (particularly at idle) may be impossible when temperatures plummet. This can create a problem inside the passenger compartment if warm coolant fails to flow into the heater core. In order to correct this condition, some vehicles utilize a fuel fired heater system. Typically, a small, pressurized fuel reservoir supplies an enclosed burner with a precisely regulated amount of fuel whenever ambient temperature falls below a certain level. The fuel fired heater injector and igniter may be automatically activated or manually activated by vehicle occupants. Coolant flows through the inline burner, where it is heated, and continues to the passenger compartment. This allows the windshield and other components to be defrosted before the vehicle is put in motion and before the engine reaches normal operating temperature.
Most often, coolant temperature sensors are used to determine heater temperature but some models also use air temperature sensors. The PCM monitors the temperature sensors to ensure that the fuel fired heater is functioning properly.
If the PCM does not detect an appropriate degree of temperature differential between coolant entering the fuel fired heater and coolant exiting the fuel fired heater, a code P2029 may be stored and a malfunction indicator lamp (MIL) illuminated. Multiple ignition cycles (with a failure) may be required for MIL illumination.
What is the severity of this DTC?
A stored code P2029 will likely be accompanied by a lack of heat in the passenger compartment. The stored code indicates that either an electrical issue or a serious mechanical failure has occurred. In really cold weather, conditions which contributed to a code of this nature being stored should be rectified as quickly as possible.
What are some of the symptoms of the code?
Symptoms of a P2029 trouble code may include:
No heat in passenger compartment Excessive heat in passenger compartment Climate control blower may be temporarily disabled No symptoms may be exhibitedWhat are some of the common causes of the code?
Causes for this code may include:
Defective temperature sensor (air or coolant) Bad fuel fired heater injector Faulty fuel fired heater burner/igniter Shorted or open wiring or connectors in fuel fired heater circuit Faulty PCM or a programming errorWhat are some P2029 troubleshooting steps?
A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle specific diagnostic information will be required to diagnose a code P2029.
You may use your source of vehicle information to locate a technical service bulletin (TSB) that matches the vehicle year, make, and model; as well as the engine size, code/s stored, and symptoms exhibited. If you find one, it could yield helpful diagnostic information.
Use the scanner (connected to the vehicle diagnostic connecto
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