Freestar exhaust leak

Sounds familiar. I had a similar issue with my old Opel Astra. Check engine light, sluggish performance. Turned out to be a tiny crack in the exhaust manifold, throwing off the sensor readings. Any chance you've got an exhaust leak somewhere? That could be the culprit, not necessarily the sensor itself.

Thanks. An exhaust leak is interesting. Where on your Opel Astra was the leak located? This might help me find it.

On my Astra, the crack was on the exhaust manifold, near where it connects to the engine block. It was hard to spot at first. It might be worth getting a professional to take a look, especially if you're not comfortable working on the exhaust system. It really does sound like a leak is messing with the temperature sensor and causing all the problems. It's difficult to diagnose without raising the car.

Based on the advice, I took the Freestar to my local workshop. There was a small but significant leak in the exhaust system, which caused the exhaust temperature sensor to give an incorrect reading. The sensor was replaced and the leak was repaired for 265€. Thanks for the help!