Mercedes Benz X-Class 2018: Black smoke, high fuel consumption and rough engine running

Hey, I can well understand your problem. I had similar problems with my 2015 Benz S-Class, especially the loss of power and increased fuel consumption. In my case, it was actually the case that the fuel filter had to be replaced. The mechanic explained to me that a clogged or faulty fuel filter can lead to severe juddering and also a bad smell. The black smoke can also be caused by unburned fuel escaping through the exhaust. This can also be the cause of the check engine light. In my case it was a serious problem as the engine could be damaged due to the bad fuel filter. However, replacing the filter fixed my problems and the car has been running perfectly ever since. So I would definitely recommend that you take a look at the fuel filter or have it looked at. Hope that helps you!

(Translated from German)

Thanks for your input, that sounds frighteningly familiar. The fuel filter really does seem to be the root of my problem. Can you remember what you paid to have it replaced? And has anything else come up since then, or has your car been running smoothly since then?

(Translated from German)

Yup, I still remember the cost. I had to fork out €45 to rectify the fault after changing the fuel filter. But since then my car has been running like clockwork. And the good news is that the fuel injection pressure has been back to the set value since the workshop visit. So I would say it was worth it. No further problems have arisen. I hope that answers your questions!

(Translated from German)

Hey, great, thanks for the quick reply! That sounds really reassuring. 45 is definitely a value I'm willing to pay to get rid of this stress. Just made the appointment with the garage and mentioned that they should check the fuel filter eventually. Hopefully my Benz will run as smoothly as yours. Really, your help is much appreciated. Thanks again!

(Translated from German)