Skoda Karoq Diesel Overheating Issue

Engine overheating and slow warm-up are definitely signs of thermostat trouble. Does your temperature gauge climb unusually high, especially when you're idling or in slow traffic? Have you noticed any coolant leaks under the car? A faulty temperature sensor could also be involved, giving you a false reading, but the slow warm-up points more towards the thermostat being stuck open. A stuck thermostat prevents the engine from reaching its optimal operating temperature quickly, and in severe cases, can lead to overheating because the cooling system isn't regulating the temperature properly.

Thanks for the quick reply! The temp gauge does go higher than usual, especially when stuck in traffic. No obvious coolant leaks though. How can I be absolutely sure it's the thermostat and not the temp sensor?

Given the high temperature readings, especially in traffic, and the slow warm-up, it's highly likely to be the thermostat. A faulty temperature sensor alone usually wouldn't cause both symptoms simultaneously. While a diagnostic scan could pinpoint the sensor's readings, replacing the thermostat is the most logical first step based on your symptoms. Our experience shows that a defective map thermostat is usually the case. If replacing the thermostat doesn't resolve the issue, then further investigation into the temperature sensor would be warranted. But given your symptoms, I'd bet on the thermostat. Book it in at a workshop. Expect around 350€.

Big thanks for the help! Dropped it off at the shop and they confirmed it was the thermostat. All fixed now, cost me 350€ as expected. Runs like a charm again!