Mercedes E Klasse Diesel check engine light problem

Incorrect fuel composition errors can be tricky. I had a similar issue with my old Volvo a few years back. Different make, different engine, but same symptoms – check engine light, rough idle. In my case, it turned out to be a faulty fuel sensor. Did the error code point to a specific sensor or component in the fuel system?

A fuel sensor Hmm, the error was pretty vague, just mentioned something about a possible defective cable or plug connection related to fuel. But yeah, that's the gist of it. Where exactly was the fuel sensor located on your Volvo And did you also experience engine knock issues

On the Volvo, the fuel sensor was near the fuel filter. But honestly, Mercedes and Volvo are worlds apart. Given that your error message points to a cable or plug, I'd start by checking those connections visually. If you're not comfortable doing that, I'd advise taking it to a trusted workshop. They'll be able to diagnose it properly and prevent any potential damage to the combustion chamber or fuel system. Better safe than sorry. Engine knock can be a symptom of incorrect fuel, but if it's a sensor issue, you might not be getting the right data to begin with.

Right, right. I was hoping it was something simple I could fix myself, but poking around the fuel system when you don't know what you're doing is probably a bad idea. Just got a quote from the workshop, and you were spot on Turns out it was a loose plug connection. They're charging me 95€ to fix it, which is a relief. Thanks for the advice