I was driving my 2002 X-Type 5-speed yesterday and felt a judder and the yellow warning light came on followed almost immediately by the red overheating light and the coolant temp gauge pegging. I pulled over and shut down the car, it didn't actually seem to be hot so I turned to key back to On and it showed a normal temp. I went on my way and it happened again, the exact same thing. The car is definitely not overheating. I searched this and it seems I'm not the first one to get this false overheating condition but none of the threads showed a definitive solution either, except it's probably not the sender. Does anyone have any thoughts on what to do here?

 

I just wanted to post a follow up to this in case anyone finds it on search. The false overheat started occurring more often, and it turned out just to be the sender. The sender is easily accessible and changed with a deep socket, no need to drain the cooling system, and a new one is only ~$10. On my multimeter the old sender was showing the correct resistance but would occasionally show fully open (meaning maximum hot). I guess the car's computer flips out when it sees this and shows a full overheat condition and doesn't go back to normal until you restart the car even if the sender goes back to showing the correct resistance. Anyway, if you're having this issue, replace the sender first since it's cheap and easy.

 

Had exactly the same on mine, most disconcerting.