Mercedes A Klasse Diesel Engine Problems

Cylinder pressure fluctuations are rarely fun Have you checked for vacuum leaks around the intake manifold or hoses A leak could throw off the pressure readings and explain the increased fuel consumption Also, what kind of diesel are you using Poor fuel quality can cause erratic combustion and trigger the check engine light I'm just suggesting simple things before you suspect major internal damage

Good point about the vacuum leaks; I'll check that this weekend Regarding fuel, I always use premium, so I doubt it's that When you say 'associated hoses', does that include the crankcase ventilation system

Yes, include the crankcase ventilation (PCV system) in your hose inspection A faulty valve or cracked hose can introduce unmetered air into the intake, mimicking a vacuum leak It's a controlled leak, but the engine management system doesn't 'know' about it If that's ok, get it to a workshop A proper scan tool can give you a better idea where the fault lies

I appreciate the insights It turns out you were right about checking it at a workshop They plugged it in and the error code was related to a sensor giving implausible readings They cleared the error, checked the sensor, and all seems fine now Repair cost 0€ I'll keep an eye on it, but hopefully, that's it