P2979 Diagnostic Trouble Code

P2979 is a kind of OBD-II Diagnostic P-Powertrain 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 P2979 diagnostic trouble code may include:

Fuel pressure too low
Rich or lean exhaust
Diminished fuel efficiency
If the DPF is not cleared the ECU will revert to the "Limp Home Mode" until the situation is corrected

Possible Causes :

A large air leak at or near the number one oxygen sensor would also cause a lean mixture.
Faulty IMRC actuator relay (if equipped)
Faulty IMRC actuator/sensor

Repair Processes :

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. 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. Look at the plug wires to make sure they are not burnt or laying on the exhaust.

Process Tips

Diagnostic trouble code P2979 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 P2979.

Fortunately, P2979 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

P2979 Trouble Code For Specific Cars

P2979 Chrysler Town And Country Exhaust Pressure Control Valve Range/Performance
P2979 Tchaika Tchaika Mirror Switch Reference Voltage Positive Common Supply Voltage Fault
P2979 Suzuki Alto Memory 1 Switch Circuit Failure
P2979 Ford Aero LF LAMP HIGH BEAM CIRCUIT Short to Battery
P2979 Mercedes Cl 55 ABS Inlet Valve Coil RF Circuit Open
P2979 Subaru Hm Left Rear Center Sensor Circuit Failure
P2979 Rover 2400 Ignition Coil - Cylinder 2 - Early Activation Fault