P315B Diagnostic Trouble Code

P315B 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 P315B diagnostic trouble code may include:

Cherry red hot catalytic converter
Poor acceleration
The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.
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)
An air leak forward of the DPF will change the sensor readings resulting in the code

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.

Process Tips

Diagnostic trouble code P315B 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 P315B.

Fortunately, P315B is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

P315B Trouble Code For Specific Cars

P315B Mercedes Cls ABS Outlet Valve Coil Rear Circuit Short To Battery
P315B Daewoo Vada Gear Control Malfunction
P315B Zagato Bravo
P315B Leblanc Caroline TCM Communication Circuit
P315B Sta Matilde Sm Lamp Headlamp Input Circuit Short To Ground
P315B Riley 1.5-litre Hood Switch Circuit Failure
P315B Skoda Fabia Kickdown Hold Relay Open or Short Circuit to Ground