P168D Diagnostic Trouble Code

P168D 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 P168D diagnostic trouble code may include:

Fuel pressure too low
Rich or lean exhaust
Diminished fuel efficiency
Reduction in engine performance, especially at low RPM levels

Possible Causes :

A faulty oxygen sensor. This will set a code in itself, however, a faulty oxygen sensor does not automatically condemn the sensor. The code just means that the sensor signal was not within specifications. An air leak or any of the above will cause an erroneous signal. There is a multitude of O2 codes relating to O2 performance which gives a clue to the problematic area.
Some aftermarket accessories and performance modifications
Faulty IMRC actuator/sensor

Repair Processes :

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. If the engine displays a miss and there wasn't a code, determine which cylinder is misfiring. If the exhaust manifold is visible, spay or pour a small amount of water on each cylinder exhaust port. Water will evaporate immediately on good cylinders and slowly on the missing cylinder. If this can't be accomplished pull the plugs and check the condition.

Process Tips

Diagnostic trouble code P168D 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 P168D.

Fortunately, P168D is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

P168D Trouble Code For Specific Cars

P168D Abarth 1600
P168D Bristol 400 Cooling Fan 3 Control Circuit Malfunction
P168D Buick Park Avenue Cylinder 9 Injector Circuit Low
P168D Lada Largus Shift Solenoid B Control Circuit Range/Performance
P168D Mitsubishi Colt Audio Reverse Aid Mute Input Ckt Failure
P168D Oldsmobile Cutlass Cylinder 8 Injector Circuit High
P168D Kia Brisa Seat Rear Up/Down Potentiometer Feedback Circuit Short To Ground