This bulletin applies to 2009 Audi A4 vehicles. The engine may be difficult to start and a rattle noise may be heard in the engine compartment. DTC P001600 or P0341 may be stored in the engine control unit. This may be due to possible damage to a camshaft or camshaft bearing surfaces.
The check valve ball in the camshaft positioner bridge may become dislodged. Fragments of the screen and the ball can restrict oil flow to the bearing bridge.
An optimized oil check valve in the camshaft positioner bridge has been available as of calendar week 23 of 2009.
* Check the non-return valve in the bearing bridge for wear.
* Check the chain tensioner.
* Check camshaft surfaces for damage.
If the screen and check valve are not damaged, replace the camshaft bridge and erase the DTC.
If the screen or check valve are damaged, inspect bearing surfaces of camshafts for scoring marks. Replace any camshaft or cylinder head that shows camshaft bearing damage.h screen and check valve in place.