P391A BMW Fault Code

Description:

The issue covered by the bulletin involves a power steering noise/whine or fluid leak from the power steering pump, gear or high pressure side power steering hose during extreme low outdoor temperature operation.

P391A Code Symptoms :

There are currently two main types of cylinder deactivation used today, depending on the type of engine. P391A code for the pushrod design which uses solenoids to alter the oil pressure delivered to the lifters. In their collapsed state, the lifters are unable to elevate their companion pushrods under the valve rocker arms, resulting in valves that cannot be actuated and remain closed.

Diagnosis And Repairing P391A

P391A OBD2 specifically refers to the camshaft (cam) timing. In this case, if the cam timing is over-retarded, the engine light will be illluminated and the code will be set.

How to fix P391A code ?

• Continuous oil flow to the VCT piston chamber
• Faulty Air Flow Meter
• Faulty front heated oxygen sensor
• Incorrect Positive Crankcase Ventilation (PCV) hose connection

One example of this would be when an bmw automatic car in placed in gear. To prevent the added drag from the torque converter and transmission from reducing the idling speed, the PCM will command the idle control valve to allow more air to enter the engine, while at the same time, adjusting the injector pulse width to inject more fuel to suit the increased amount of air. Note that the idle air control valve is closed by the PCM when the throttle plate is opened to prevent excess air from entering the engine.