Insignia Overheating Slow Warm Up

Overheating and slow warm-up on the Insignia often points to a thermostat problem. Has the cooling fan been running constantly, even from a cold start? Any sign of coolant leaks around the thermostat housing?

Thanks. I haven't seen the cooling fan running constantly from a cold start, but I'll keep an eye on it. No visible coolant leaks around the thermostat housing either. Anything else I should inspect to confirm a defective thermostat?

Given the symptoms and no visible leaks, it highly suggests a defective map thermostat. That's the most common culprit. Other issues could be involved, but it's less likely. Diagnosis can be tricky without proper equipment, so I'd recommend a workshop visit.

Thanks for the advice. I'll book it in with my local workshop for a diagnosis. A defective thermostat sounds right. The repair cost was 350€.