Peugeot 308 Transmission Oil Temperature Sensor Fault

I had a similar issue with my old Opel Insignia a few years back. Engine was also diesel. The symptoms sound very familiar – warning lights, rough shifting. In my case, it turned out the gearbox oil level was too low, which was causing the temperature sensor to trigger the warnings and affecting the gear changes. Have you checked your gearbox oil level?

Thanks for the quick reply! I haven't checked the gearbox oil level myself yet, to be honest. Is it something relatively easy to do, or does it require special tools or knowledge? And if the oil is low, would simply topping it up solve the problem, or could there be a leak somewhere that needs addressing first? I am not familiar with transmission issues...

It's best to have it checked professionally. While topping up the oil might temporarily solve the issue, a persistent low level usually indicates a leak, which needs to be identified and fixed to prevent further damage. Ignoring it could lead to much more expensive repairs down the line. With those symptoms, I wouldn't risk further driving before a proper inspection.

Thanks for the advice. I took it to a local mechanic, and you were spot on! Turns out the gearbox oil level was indeed low, causing the sensor to go haywire. They found a small leak, fixed it, and replaced the sensor. The total cost was 365€. Everything seems to be running smoothly now. Really appreciate your help!