P303B Diagnostic Trouble Code

P303B 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 P303B diagnostic trouble code may include:

Excessive exhaust leak
Hesitation upon acceleration
Malfunction Indicator Lamp (MIL) illuminated
The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.

Possible Causes :

An air leak forward of the DPF will change the sensor readings resulting in the code
Rusty exhaust systems, cracked exhaust manifolds or damaged or missing gaskets or donuts will cause air leaks.
Low fuel pressure caused by a clogged filter, failing fuel pump, failed fuel pressure regulator or clogged or leaking injectors.

Repair Processes :

Use the DVOM to test resistance and continuity on all system circuits if actuator and sensor resistance levels are in compliance with manufacturer's specifications. 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.

Process Tips

Diagnostic trouble code P303B 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 P303B.

Fortunately, P303B is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

P303B Trouble Code For Specific Cars

P303B Du Pont Touring Illuminated Entry Input Open Circuit
P303B Maserati 124 Transmission 4-Wheel Drive Mode Select Short Circuit To Ground
P303B Ferrari 275 Input/Turbine Speed Sensor Circuit Range/Performance
P303B Porsche 718 Front Sounder Circuit Short to Vbatt
P303B Jaguar Xk8 Seat Driver Occupied Switch Circuit Short To Battery
P303B Frazer Nash Continental No Movement Detected After an Unlatch During Power Open
P303B Opel Meriva A Door Ajar Circuit Short To Ground