Peugeot 807 cylinder pressure fluctuations

Hello there! I also own an 807. Your symptoms sound awfully familiar. Cylinder pressure issues can be tricky. Before diving into worst-case scenarios like piston rings or a head gasket issue, have you considered that this could be a consequential error? Meaning, the pressure fluctuations might be a symptom of something else failing, rather than the primary cause? For example, a faulty sensor somewhere, or maybe even something related to the timing belt or camshaft position? Because if that's the case, you would not want to look into the engine itself, but rather fix the faulty part that is causing these wrong readings.

Thanks for the quick response! A consequential error makes sense. I was getting worried about piston rings. When you had similar symptoms, what was the 'something else' that was failing?

Okay, so mine was a bit of a saga. I strongly advise that you visit a workshop, because it seems that your engine is misfiring and it can damage the other parts. In my case, initially, the garage thought it was the EGR valve causing havoc, but after replacing it, the problem persisted. Eventually, they traced it back to a dodgy fuel injector that was causing an imbalance in the combustion, because this was sending incorrect signals to the engine management system. The lesson I learned is, don't always trust the first error code you see!

Thanks for the insight! I'll definitely take it to a workshop and mention the possibility of a 'consequential error' and the injectors. It was a faulty sensor, as you suggested. The repair was covered and it cost me 0€.