Mercedes C Klasse Diesel VANOS Solenoid Issue

I have seen similar issues with the M111 engine. Given the symptoms you describe, a faulty VANOS solenoid valve is a plausible diagnosis. Before replacing it, inspect the wiring harness and connector for corrosion or damage. Confirm that the solenoid is receiving the correct voltage. Have you checked the camshaft timing with a diagnostic tool?

Thanks for the quick reply Wiring harness looks okay, no obvious corrosion there. I haven't checked the camshaft timing with a diagnostic tool yet, but I'll add that to the list. When you had a similar issue, were the engine misfires constant, or intermittent? And did replacing the VANOS solenoid completely resolve it, or were there other gremlins lurking?

In my case, the engine misfires were intermittent initially, becoming more frequent over time. Replacing the VANOS solenoid did resolve the issue completely. However, I would recommend having a workshop perform a thorough diagnosis before replacing any parts. They can use more sophisticated tools to pinpoint the problem.

Appreciate the insight Sounds like a trip to the workshop is inevitable. I'll advise on the thread once I've got a diagnosis and resolution. Turns out it was the VANOS solenoid valve indeed Replaced it, and the check engine light is gone, fuel consumption is back to normal, and the engine is purring like a kitten. Thanks again for the guidance