Mercedes CLA Diesel Reset Quantity Drift Compensation Error

Rough running and a drift compensation error definitely point towards fuel delivery issues. It's like your engine's trying to balance a wobbly table by constantly adjusting the legs. Have you checked your airflow sensors? Sometimes a faulty sensor can mess with the fuel mixture and trigger similar errors. Also, what's your fuel economy been like lately? A sudden drop could indicate an injector problem. Before replacing anything, have you tried any compensation adjustment or reset procedure?

Airflow sensors seem okay, at least according to the diagnostics. Fuel economy has taken a slight dip, nothing major. As for a compensation adjustment, is there a specific procedure you're thinking of? I've seen some generic reset procedures online, but I'm hesitant to just start randomly fiddling without knowing what I'm doing.

It's wise to be cautious. Randomly resetting things can sometimes make matters worse. Given the symptoms and the error code, a defective injector is the most likely culprit. The 'drift compensation' is the ECU's attempt to correct for an injector that's not performing as it should. Think of it like a musician constantly tuning a string that won't stay in tune. Since you've already checked the airflow, and the fuel economy is down, I'd recommend getting the injectors properly diagnosed by a workshop. They have the tools to test each injector individually and confirm if one is indeed faulty.

I appreciate the advice. I took it to a workshop, and you were spot on – one of the injectors was faulty. They replaced it, cleared the error codes, and the engine's running smoothly again. The bill came to 515€. Thanks for pointing me in the right direction!