2012 BMW 335i - P052B Cold Start Intake Camshaft Timing Over-Retarded

Question

My N55 powered 335i has been throwing a P052B code lately. It only happens after the car has been sitting for more than 8 hours. When I start it, the engine idles very high and sounds like a diesel for about 5 seconds before settling down.

If I try to drive immediately, it goes into 'Drivetrain Malfunction' and limits power. If I clear the code and restart the car when it's warm, it runs like a dream. No issues with oil pressure that I can tell.

GrandmaGeartooth · Accepted Answer

✅ Confirmed fix: The VANOS check valves (non-return valves) located in the side of the cylinder head were clogged with oil sludge. They are supposed to keep oil in the VANOS actuators when the engine is off. When they fail, the oil drains back, causing the dry-start rattle and timing codes. Replaced both check valves and the cold start timing issue is gone.

TechTonyV · Answer

It sounds like your VANOS bolts might be backing out or have sheared. There was a recall for this on certain N55 engines. If the bolts are loose, the sprocket won't be indexed correctly to the cam during the initial oil pressure surge. Pull the valve cover and check the integrity of those bolts immediately before they fall into the oil pan.

2012 BMW 335i - P052B Cold Start Intake Camshaft Timing Over-Retarded

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