M Klasse Hybrid Engine Uneven Running

Interesting issue I also own a Mercedes M Klasse hybrid and encountered something similar Jerking rough idle Does the rough idle happen mostly when the engine is cold Did you check for any obvious exhaust leaks visually or with a smoke test Before jumping to fuel injectors or the timing belt which would be more involved have you considered the oxygen sensor Its a common failure point and can cause those symptoms Is the check engine light on constantly or does it come and go

The rough idle does indeed seem more pronounced when the engine is cold I have not yet performed a smoke test but a visual inspection did not reveal any obvious exhaust leaks Regarding the oxygen sensor is there a reliable method to test its functionality or is replacement the more prudent course of action The check engine light is intermittent appearing and disappearing seemingly at random

Since the idle is worse when cold and the check engine light is intermittent it does sound like it could be the oxygen sensor Testing it requires some specialized equipment and knowledge Considering the symptoms and the age of the vehicle I would suggest a qualified workshop performs a thorough diagnostic check especially of the exhaust system for leaks Its better to confirm the source of the problem rather than replace parts blindly In my case a small exhaust leak near the manifold was causing similar issues

I appreciate your advice I took the vehicle to a reputable workshop and as you suspected a leak in the exhaust system was indeed the root cause of the problem The repair cost amounted to 265€ Thank you again for your assistance in diagnosing this issue