Serena exhaust back pressure sensor issue

I see. The symptoms do point to a faulty exhaust back pressure sensor. Have you checked the sensor's wiring and connectors for any obvious damage or corrosion? A visual inspection might reveal a simple fix before condemning the sensor itself.

Thanks for the quick response. I did a quick check of the wiring harness, but nothing jumped out at me. Is there a way to test the sensor itself with a multimeter, or would that be a waste of time without proper specifications?

While you could technically test the sensor with a multimeter, obtaining accurate specifications for a 2003 Serena diesel exhaust back pressure sensor might be difficult. Given the symptoms, it's likely the sensor is indeed defective. At this point, a workshop visit seems advisable.

You're absolutely right. I took it to a trusted workshop, and indeed, the exhaust back pressure sensor was the culprit. Replacement cost me 245€. Problem solved. Thanks for your help!