XC90 Temperature and Check Engine Light Issues

Dude, that sounds super annoying! I had a similar problem with my old Subaru Forester – the check engine light kept popping on, and it took forever to heat up. Turns out, the thermostat was stuck open. A thermostat is a valve that regulates the flow of coolant to your engine. Have you checked your coolant level? A low coolant level can cause all sorts of weird temperature readings. Also, is your radiator fan running constantly?

Thank you for the suggestion. I will check the coolant level. The radiator fan is not running constantly. Could you elaborate on the function of the thermostat in relation to the symptoms I described?

Yeah, so a thermostat basically controls how quickly your engine warms up. When it's cold, the thermostat stays closed, forcing the coolant to circulate only within the engine block, so it heats up faster. Once the engine reaches operating temperature, the thermostat opens, allowing coolant to flow through the radiator to prevent overheating. If it's stuck open, the engine never really gets up to temp, which explains why it takes so long to warm up and why you're getting those error codes. Honestly, though, with those symptoms, it could be a bunch of things. I'd suggest taking it to a workshop; they can hook it up to a diagnostic tool and pinpoint the exact problem.

I appreciate the clarification. I have taken the vehicle to a workshop. The diagnostic revealed a defective fuse, as initially suspected. The total repair cost was 52€.