How to fix engine knock (pinging) on Citroen Xantia?

[NorwegianMan]

My car is 1998 Xantia X1, 110 hp, petrol
Lately I have engine knock (low ping sounds) due to heavy load on the engine. This only happens when the engine reaches operating temperature. No warning lights come on on the dashboard when this happens. The spark plugs look good (only light grey), and I have also switched to new ones. I have tried to switch to 98 octane petrol, but the problem does not go away. Both radiator fans work, and the temperature gauge rarely exceeds 80 degrees, so it seems as if the cooling of the engine is in order. So could it be the knock sensor that is faulty? I understand that the sensor on these engines consists of a small microphone, but where is the sensor located on the engine? I have tried to look for it but can not find it.

[peter306]

Hello, according to Haynes 1993 to 1998, on later models the knock sensor is screwed onto the rear face of the cylinder block, jack it up and support it then access can be gained from underneath. neither of the manuals have a photo.
I'm sure someone with greater knowledge than me will be along soon.
Peter

[NorwegianMan]

Thanks peter 306, then I probably will find the knock sensor, but maybe the engine knock can be due to too much carbon buildup in the combustion chamber? Can it be heavy carbon buildup there even if the spark plugs electrodes only is light grey as mine is?

[xantia_v6]

Unless there is a significant problem with the mixture, carbon build-up should not be an issue with this engine.

A diagnostic session with a tool that reads live data should tell you if the knock sensor is detecting any knock.