XTrail Temperature Readings Check Engine Light

Those symptoms sound familiar. I had a similar experience with my old BMW 3 series, although the engine was petrol. Incorrect temp readings, check engine light... it was a pain. Have you checked for any physical obstructions blocking the grille? Leaves, debris, anything like that? Also, do you know if your XTrail has an electric fan on the radiator? If it does, is it kicking in at all?

I've checked the grille and it seems clear. I'm not sure if I have an electric fan on the radiator, or how to check if it's working. Where is it located and how can I evaluate its operation?

The electric fan sits right behind the radiator. Usually, when the engine starts getting hot (but not necessarily overheating), you should hear it kick in. If you're not hearing it, that could be a problem. Honestly, though, with those symptoms, especially the check engine light, it's probably best to get it checked by a workshop. They'll be able to diagnose it properly.

I took it to a workshop and it was a defective fuse causing the cooling grille to be restricted, like the forum suggested! A fuse replacement fixed it. The repair cost 52€.