BMW Z3 with check engine light

Vehicle Details: 2000 BMW Z3 2.5L, Automatic Transmission, M54 Engine, 35465 Miles

Technician: Tyler

Initial Condition:

  • Check engine light on
  • Engine is running rough
  • **had recent oil change

Diagnostic Process:

Scanned vehicle and found the following faults In the Engine control module (DME):

  • P1522 control VANOS position inlet camshaft
  • P1520 control VANOS end position fault, exhaust camshaft.
  • Ran test plan for the VANOS control on both the intake and exhaust and discovered that the VANOS degree angles were not changing.
  • Removed oil filter cap and inspected oil filter, looked newer and was not plugged.
  • Removed the filter and found that the oil filter housing had been broken from someone doing an oil change.
Broken oil Filter Housing

Broken oil Filter Housing

  • Removed all of the remaining pieces of metal that were in the oil filter housing and replaced the broken oil filter housing unit.
  • Started the car and re-Ran VANOS tests and again found that The VANOS degree angles were not changing.
  • Removed the VANOS and disassembled and found that there was a piece of metal inside the unit that was causing the exhaust VANOS valve to hang up in its bore and not allow oil pressure to the VANOS gear/Timing actuator causing the angles not to change.
Vanos disassembled

Vanos disassembled

Replaced the VANOS Unit with a rebuilt one and test drove the car and reran the VANOS tests and the car is performing well now.


The client confessed to doing his own oil change and not being able to remove the oil filter cap.  As a result excessive force was used on the filler cap causing the internal metal flange to break.  Had he then replaced the oil filter stand before proceeding further the vanos would probably not have been damaged.  This is one of those tougher lessons to learn about not ignoring something that is broken.  End result was good:  the car runs well now.  Had more metal circulated through the lubrication system there could have been much more extensive engine damage.  Great work Tyler on figuring this one out!