Saxo diesel charge air temperature sensor fault

Interesting. I had something similar happen with my Saxo, though I don't remember the exact year. Did you see any temperature fluctuations when the error was present? It could be a faulty airflow sensor, but the hissing makes me think it's an air leak.

Thanks for the reply. I didn't check the temperature specifically. Could these symptoms point to other bad parts? Is the air sensor easy to get to? And would a bad cable or connection always cause these issues?

Well, I can't say for sure about other parts. The hissing and power loss together is a strong sign of a leak. If you're not comfortable working in the engine bay, a Citroen mechanic should be able to figure it out quickly.

Thanks for the advice. I took it to a local mechanic, and they confirmed it was the charge air temperature sensor circuit, the cable was bad. It cost 95€ to fix, but it's running great now!