C1 diesel engine sluggish check engine light

A faulty manifold pressure sensor definitely can cause those symptoms! The sensor provides crucial data to the engine control unit (ECU) about the air pressure in the intake manifold. If the readings are off, the ECU might miscalculate the air-fuel mixture, leading to reduced power, poor response, and increased fuel consumption. Have you checked for any obvious vacuum leaks around the intake manifold? Sometimes a leak can trigger a false reading from the sensor.

Thanks for the quick reply! I haven't specifically looked for vacuum leaks, but I did visually inspect the hoses around the intake manifold. Is there a particular area I should focus on when looking for these leaks? Are there any tests I can easily perform at home?

Since you're getting a manifold pressure sensor code and experiencing those symptoms, a vacuum leak is a prime suspect. Focus on any hoses or connections directly attached to the intake manifold. Cracks, splits, or loose connections are common culprits. You might be able to hear a hissing sound near a leak while the engine is running. Unfortunately, pinpointing a leak precisely often requires specialized tools like a smoke tester. Considering the symptoms and potential for misdiagnosis, it might be wise to take it to a workshop. They'll be able to accurately diagnose the issue and ensure the repair is done correctly.

Thank you so much for the detailed explanation! I really appreciate the advice. I took it to a local garage, and as you suspected, there was a large vacuum leak. They replaced a cracked hose and the manifold pressure sensor just to be safe. Total cost was 235€, but the car is running perfectly now!