A common problem with the Dual Vanos after a rebuild or installing a new/rebuilt vanos is the p0012/p0014 fault codes. Generally this means that either the intake or exhaust camshaft is not advancing, or is stuck in one position. This could be caused by a couple of different things but generally it's due to a stuck solenoid piston. Fortunately it's an easy fix and does not mean there is a defect or malfunction with the vanos itself.
How to check the solenoid piston -
- Determine which camshaft the fault code is reporting as stuck.
- The p0012 is for Intake and p0014 is for exhaust.
- Remove the solenoid from the vanos using a 32mm socket or wrench
- Push the control piston with your finger to see if it will move
- The piston should compress against the spring then rebound back
- If not, carefully remove the piston from the bore
- Clean the piston, oil and reinstall it
- Check to see that it moves freely when pressed down
- Reinstall the solenoid and plug in connector
The issue is caused by debris getting stuck between the piston and it's bore. The clearance is extremely tight and even the smallest particle can jam the piston in place. When the engine is first started after a installing the vanos the high oil pressure will quickly fill the vanos and this can sometimes flush out tiny particles of debris. The debris can cause the piston to stick thus causing the 'stuck cam' fault code.