Traveller temperature gauge issue

Sounds familiar. I had a similar problem with my 2017 Opel Insignia. Same symptoms: weird temperature readings and the engine light. Have you checked the fuse for the cooling system? On my Opel, a defective fuse was causing the cooling grille to stay restricted, messing with the engine temp.

A fuse, huh? I hadn't thought of that. Where exactly would I find that fuse? And is it something I can easily check myself, or am I better off taking it to a mechanic?

On my Insignia, the fuse box was under the hood, near the battery. Check your owner's manual; it should have a diagram. You can pull the fuse and see if the filament is broken. If it is, replace it with the same amperage. If that doesn't fix it, or you're not comfortable doing it, then a workshop visit is probably the best bet.

Thanks a bunch for the tip! Turns out it WAS the fuse for the cooling grille, just like you said. A quick trip to the shop, a new fuse, and 52€ later, everything's back to normal. Really appreciate the help!