P303F Diagnostic Trouble Code

P303F 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 P303F 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 :

If the scan tool has that capability, and the scan tool can operate the IMRC valves, then the problem is either resolved and a simple code clearing is all that's left or a new PCM would be called for. 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. Replace the oxygen sensor that is downstream from the catalytic converter on the side of the engine that does not contain cylinder #1. Also, if a oxygen sensor code stating "heater circuit malfunction" the sensor has most probably failed.

Process Tips

Diagnostic trouble code P303F 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 P303F.

Fortunately, P303F is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

P303F Trouble Code For Specific Cars

P303F Nash Statesman CD-ROM Error
P303F Peugeot Tepee Engine Oil Pressure Sensor/Switch Low Voltage
P303F Hyundai Hcd
P303F Nissan Livina Column Tilt Feedback Potentiometer Circuit Open
P303F Ford Maverick Mirror Driver Vertical Feedback Potentiometer Circuit Failure
P303F Simca 1100 Intake Manifold Runner Control (Bank 2) Stuck Closed
P303F De Soto Powermaster Horn Relay Coil Circuit Failure