Safrane Exhaust Temperature Sensor Issue

Greetings. Your symptoms do point towards a possible issue with the exhaust temperature sensor. I had a similar problem with my old Opel Vectra; same symptoms, although it was a petrol engine. Have you noticed any unusual noises or smells coming from the exhaust system? Perhaps a leak could be affecting the sensor readings and causing temperature fluctuation.

Thank you for your reply. I haven't specifically noticed any unusual noises or smells, but I also haven't thoroughly inspected the exhaust system for leaks. Is there a way to check it myself without special equipment?

While a visual inspection might reveal obvious damage, detecting smaller leaks can be challenging without proper equipment. Considering your symptoms and the age of the vehicle, a leak in the exhaust system affecting the exhaust temperature sensor is a plausible cause. I would recommend taking it to a workshop for a professional diagnosis to avoid further complications to the engine management or emission control systems.

I appreciate the advice. I took the car to a workshop. Indeed, there was a leak in the exhaust system, which caused the sensor to fail. The total repair cost, including sensor replacement, was 265€. Thanks again!