P21AB BMW Fault Code

Description:

Variable Cam Timing Over-advanced (Bank 1) The comprehensive component monitor (CCM) monitors the VCT position for an over-advanced camshaft timing.
The test fails when the camshaft timing exceeds a maximum calibrated value or remains in an advanced position.

BMW cam timing improperly set No oil flow to the VCT piston chamber Low oil pressure VCT solenoid valve stuck closed Camshaft advance mechanism binding (VCT unit) P21AB DTC is a check of the VCT unit.

P21AB Code Symptoms :

There are currently two main types of cylinder deactivation used today, depending on the type of engine. P21AB 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 P21AB

P21AB OBD 2 code on vehicles with electronically controlled automatic transmissions, the 3-4 shift solenoid is responsible for actuating the hydraulic circuits to activate clutches or bands that change gears inside the automatic transmission.

How to fix P21AB code ?

• Erratic camshaft position due to low oil pressure
• Clogged or faulty fuel injector (s)
• Faulty Intake Valve Timing Control Solenoid Valve
• Three way catalyst converter Bank 1

Some systems require that the actuator has an adequate supply of brake fluid. Low brake fluid levels can mimic the symptoms of code P21AB, so consult the manual to locate the brake fluid reservoir.

Bear in mind that a low fluid level can set code P21AB on some applications, so make sure that on fluid operated systems the fluid level is up to the mark before starting an electrical diagnosis.