Mercedes SLC Diesel Engine Issue

I had a similar issue with my SLC, though I don't remember the exact error code. Your symptoms match those of a failing injector. The engine roughness and check engine light show an imbalance in fuel delivery. The drift compensation is the ECU's attempt to fix injector issues. The engine control unit tries to compensate for deviations in the fuel injected quantity, usually from wear, or carbon deposits on the injectors. Have you seen changes in fuel use or unusual exhaust smells?

Thanks for the input. I hadn't noticed a big change in fuel use, but I wasn't watching closely. Exhaust smells seem normal. Did the reset quantity drift compensation error also appear in your diagnostics? And did injector replacement fix it?

Yes, the diagnostics showed a drift compensation issue, but I don't recall the exact wording. Injector replacement did solve the problem. Given the symptoms and error code, a workshop with Mercedes-Benz tools is a good idea. They can test injectors to check function and find the faulty part. They can measure the backflow of each injector. High backflow often means internal leakage and injector failure.

Thanks for confirming. I'll book my mechanic to check the injectors and likely replace them. The estimated cost is around 515€, which seems fair. Thanks again for the advice.