Citan diesel engine trouble power loss and hissing sound

That sounds awfully familiar! I drive a Citan as well and had almost identical symptoms. Check engine light, power loss, and that distinctive hissing – it was driving me crazy! In my case, the air temperature readings were fluctuating wildly. Did you notice anything like that, or any other issues with the air sensor readings?

Temperature fluctuation... interesting. I haven't monitored the temperature gauge closely enough to confirm that specifically. Was it a straightforward fix for you? Did you end up replacing the charge sensor completely, or was it just the wiring like I suspect?

Sadly, I didn't manage to fix it myself. Although I checked the sensor and the connection, I didn't find anything visually wrong. I ended up taking it to a workshop. They confirmed the charge air temperature sensor error and replaced a faulty wire. If you aren't comfortable doing electrical diagnostics, I suggest a visit to a professional. Better safe than sorry!

Thanks for the insight! I appreciate you confirming a similar experience. I checked the wiring myself, but couldn't spot anything obvious. I took it to the shop as you suggested, and you were right – it was a faulty wire connection. The bill came to 95€ including the diagnostics and repair. The Citan is running smoothly again!