Yaris diesel temperature issues

That sounds familiar! I had a similar issue with my old Opel Astra. Same symptoms – engine taking forever to warm up, check engine light, temperature weirdness. In my case it ended up being a faulty thermostat, but a restricted cooling grille could definitely cause similar problems. Have you tried visually inspecting the radiator for any blockage?

Thanks for the insight! I did a quick visual inspection of the radiator, but I'll take a closer look. When you say "faulty thermostat", do you mean it was stuck open, preventing the engine from reaching operating temperature? Also, did your Opel throw any specific error codes related to the cooling system?

Exactly! The thermostat was stuck open, constantly circulating coolant and preventing the engine from warming up properly. As for error codes, I honestly can't recall the exact ones. It's been a while. If you've checked the basics and you are still facing issues, it might be time to visit your local workshop. Better to be safe than sorry, especially with a diesel engine.

Appreciate the help! Took it to a shop, and you were right – the thermostat was indeed stuck open. They also found a blown fuse related to the cooling fan, which might have contributed to the problem. Total cost was 52€ Thanks again!