S10 Overheating Slow Warm Up

I experienced a similar issue with my S10. Have you checked for any coolant leaks? A faulty temperature sensor could also produce these symptoms. Inspect the cooling system thoroughly before assuming it is the thermostat. A diagnostic tool might help pinpoint the exact issue.

Thanks! I did check for coolant leaks, didn't see anything obvious. Where exactly is the temperature sensor located on the S10? Could a bad sensor really cause both overheating AND slow warm-up?

The temperature sensor is typically located near the thermostat housing. A defective sensor can indeed cause inaccurate readings, leading to both overheating indications and prolonged warm-up times as the engine management system misinterprets the engine temperature. Considering the symptoms, and based on my experience, I recommend taking it to a workshop for a professional diagnosis, as a defective map thermostat is often the culprit.

You were spot on! Took it to the shop, and it WAS the thermostat. Cost me about 350€ to fix, but at least it's running normally again. Thanks so much for the advice!