Mercedes GLE hybrid knock sensor issue

That's interesting. I had similar symptoms on my old Volvo: warning light and higher fuel consumption. Did your mechanic pinpoint which knock sensor is faulty? Did they test the wiring harness before deciding it was the sensor? Mine was a corroded wire, not the sensor. Was the car's performance really bad or just a little sluggish?

He mentioned checking the component's cable and plug connection, but wasn't specific. How did you diagnose the corroded wire on your Volvo? Was it obvious, or did it require special tools?

The auto repair shop wanted to replace the sensor, but I pushed them to investigate the wiring first. I think they used a multimeter to check for continuity. If your mechanic only briefly mentioned the wiring, I'd suggest asking them to double-check it thoroughly before replacing the sensor. Replacing parts is easy money for them. I'd hate for you to spend 95€ and still have the same car problems. I'd advise to go to a workshop.

I followed your advice and asked the mechanic to take a closer look at the wiring. It was a corroded connector, just like you suspected. They cleaned it, and the problem seems to be resolved. The check engine light is off, the fuel consumption is back to normal, and the engine is idling smoothly again. Thanks a lot for saving me from an unnecessary knock sensor replacement!