C30 check engine light and power loss

I had similar symptoms in my C30. Could be a faulty exhaust temperature sensor. This can trigger the check engine light and impact the engine's performance. Anything unusual with the exhaust system, like a strange smell or sound?

I haven't checked for exhaust abnormalities. What causes this sensor to fail? Is this related to emission control?

My issue was a small leak in the exhaust system, which damaged the exhaust temperature sensor. Sensor replacement solved the problem and improved emission control. Get it checked at a workshop. If it's faulty, it needs prompt replacement.

Took your suggestion and had the car examined. Faulty exhaust temperature sensor, likely from a minor exhaust leak as you said. Replaced the sensor, total cost was 265€. The car is running smoothly now.