Thalia Knock Sensor Issue

Sounds familiar! I had a similar problem with my Thalia. The symptoms are almost identical: check engine light, terrible fuel efficiency, and that shaky idle. In my case, it turned out to be exactly what you suspect: the knock sensor. Did you check the cable and plug really thoroughly? Sometimes the damage is hidden. Also, have you tried clearing the error code to see if it comes back?

Thanks for the reply! When you say 'hidden damage,' what do you mean exactly? I visually inspected the plug and cable, and nothing jumped out at me. I haven't cleared the error code yet, mainly because I don't have a code reader. Is there a way to check the sensor itself to see if it's actually faulty, or is it just a case of replacing it and hoping for the best?

By hidden damage, I mean corrosion inside the plug, or a broken wire inside the insulation that you can't see with the naked eye. Honestly, without proper diagnostic tools, it's tough to be 100% sure. You could try cleaning the contacts with electrical contact cleaner, but it might be worth taking it to a workshop to get a proper diagnosis. They can test the sensor and wiring properly. In my case, I ended up going to the workshop because I couldn't figure it out myself.

Alright, thanks for the advice! I took it to a local mechanic, and you were spot on – it was the knock sensor connection! Apparently, there was corrosion inside the plug that I couldn't see. They cleaned it up and replaced a small section of the cable. Cost me 95€, but at least the check engine light is off, the fuel consumption is back to normal, and the engine idles smoothly again! Thanks again for pointing me in the right direction.