07 Volvo S40 Diesel Overheating Issues and Possible Faulty Coolant Thermostat

Hey, sounds like a hassle. I had a pretty similar problem with my '05 Volvo V50. I'm no mechanic, just a guy with some experience fiddling with cars. I took it to my local workshop. Turned out, it was damage to the wiring harness, cost me about 110 Euro to get it sorted. Maybe that's your issue as well? Could you share more on your car's maintenance history? It could help with a more specific suggestion. Cheers!

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Hey there, thanks for your input. The car's got quite a journey under its belt with 196,756 KM so far. Last I took it in for a service was around 5000 km ago, no major issues then. Checked the performance of the cooling system, oil change, filters and belts. Wiring harness sounds like a possibility, I didn't consider that. I'll look into it. Thanks again!

(Translated from German)

No worries! Incredible mileage you got there on the Volvo - solid as a rock, these cars. The whole wiring harness issue I had was a pain, but once it was sorted, the car's been running smoothly. With the decent service history and recent tune-up you've mentioned, it does seem like a possible culprit, especially given the high mileage. And since the problem's persisting even after addressing the cooling system, it probably isn't a coolant thermostat malfunction after all - though, always good to have such things checked. If you're planning to get the harness issue checked, do remember, it might take a bit of time and probing around to find any faults. The mechanic might need to go through each circuit one by one. In the meantime, also check if the coolant level is low or if there's possible leakage. Sometimes, the simplest things can cause the most frustration. Good luck with it all! Keep us posted on how it goes.

(Translated from German)

You've been of great help! I really appreciate your detailed response. It's given me a clearer point of view. I loved how you mentioned it could be the simplest things, will definitely check the coolant level first before anything else. Quite a bummer when a car you love starts acting up, but that's the game, isn't it? Will get an appointment with my mechanic, let's see how it turns out. Will keep you guys updated! Thanks again for the advice, cheers!

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