Mercedes S Klasse Hybrid Engine Stalling After Fuel Filter Change

The symptoms you describe check engine light engine stall at idle and reduced power certainly point towards a fuel system issue. The fact that it occurred after a fuel filter change is highly suggestive. An engine misfire could also be a symptom. A faulty fuel regulator even a slightly defective one can cause inconsistent fuel delivery leading to these problems. The 'check engine light' indicates that the car's computer ECU has detected a problem and stored a diagnostic trouble code DTC. It's plausible that air entered the fuel system during the filter change or the regulator itself was disturbed. Did you ensure the new filter was properly seated and all connections were tight? A diagnostic scan should reveal the specific DTCs and confirm the fuel regulator's status.

Thank you for your quick response. I will check the fuel filter seating and connections again. Concerning the diagnostic scan can a generic OBD2 scanner accurately identify a fuel regulator issue or would a more specialized Mercedes diagnostic tool be required?

A generic OBD2 scanner might give you a general code related to fuel pressure but a Mercedes-specific diagnostic tool is definitely preferable. These tools can access more detailed information and perform specific tests on the fuel system including the fuel regulator. The diagnostic trouble code DTC reported with a generic OBD2 scanner may be too ambiguous. In some cases a faulty fuel regulator can also impact fuel efficiency so monitor that as well. I would recommend a visit to a qualified workshop. The car might have an error entry and the regulator might need a reset. This is a very common issue especially with hybrid engines. The regulator itself rarely breaks.

I appreciate the advice. I took the vehicle to a local workshop and indeed the diagnostic tool revealed an error entry related to the fuel regulator. It appears that after changing the fuel filter the system needed a reset. The mechanic reset the fuel regulator and the check engine light is now off the engine runs smoothly and the power has returned. The entire repair cost me 45€. Thank you again for your assistance.