C0439 Diagnostic Trouble Code

C0439 is a kind of OBD-II Diagnostic C-Chassis Diagnostic Trouble Code.

It is considered generic because it applies to all makes and models of vehicles, although specific repair steps may be different depending on your car model.

Symptoms

Symptoms of a C0439 diagnostic trouble code may include:

The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.
Faulty PCM
If the DPF is not cleared the ECU will revert to the "Limp Home Mode" until the situation is corrected
Diminished fuel efficiency

Possible Causes :

Rough running engine due to misfiring plugs. Many engines have misfire codes to indicate the cylinder effected, such as P0307 for number 7.
Rarely - faulty Powertrain Control Module (PCM-programming required after replacement)
An air leak forward of the DPF will change the sensor readings resulting in the code

Repair Processes :

Look at the plug wires to make sure they are not burnt or laying on the exhaust. With the valve disconnected, the red voltmeter lead should be attached to the IMRC valve power wire and the black voltmeter lead connected to ground. Check to make sure they are not burnt or corroded. If in doubt, get some Electrical Contact cleaner at any parts store if cleaning of the terminals is needed.

Process Tips

Diagnostic trouble code C0439 is not difficult to diagnose and repair. Thus, it always pays to have a qualified technician to look after your vehicle should this error code arise.

Diagnosing this code requires the engine to be in good running shape, without unmetered air entering the engine. If other codes that relates to misfiring condition, lean running or air entering the engine is present, then you must first fix those error codes before C0439.

Fortunately, C0439 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

C0439 Trouble Code For Specific Cars

C0439 Daimler 3-litre Hazard Flash Output Circuit Open
C0439 Toyota Alphard Normal/Performance Switch Circuit Malfunction
C0439 Rover 45
C0439 Pontiac Grand Safari Exhaust Valve Control Solenoid Circuit Range/Performance (Bank 2)
C0439 Marcos Mantis Transmission 4-Wheel Drive Clutch Relay Open Circuit
C0439 Saipa Nasim Ignition/Distributor Engine Speed Input Circuit Malfunction
C0439 Jeep Station Wagon Seat Driver Recline Backward Circuit Short To Battery