So hoping someone in the know will have some ideas.

Had a guy come to me after his temp gauge playing up going to the red then going back to half way and the engine being fine and not actually over heating so it seems.

I replaced the Temp sensor as they are a common fault and the problem is still there! So just to be comfortable in my own mind to let him go with the car i changed the thermostat and replaced the whole circuit of coolant with fresh stuff! The gauge is still the same.

The thermostat is a 82c jobby. I have plugged into the OBD port and the engine reads around 120c and once it hits 122c the temp gauge goes haywire and the fans kick in as they should. And temps read as high as 131c just normal driving 60mph on a carriageway.

I would also like to note as anyone who knows this engine will know that the temp sensor is situated in between cylinder 2 and 3 plug in the rocker cover and is no way incorporated into the coolant system so its a Engine temp more than a coolant temp.

The car uses no oil or water and it on around 80k miles and the car itself it on 186k.

Any ideas throw them my way