Peugeot 5008 rough running hissing noise

Sounds familiar. I also drive a Peugeot 5008 diesel and experienced similar symptoms not too long ago. The hissing, rough running, and power loss point towards a potential issue with the intake manifold flap. Basically, the intake manifold distributes air to the engine cylinders and the flaps control how the air flows. If they're not working properly, it can seriously mess with engine performance.

Thanks! So, how did you fix it? Was it definitely the intake manifold flap control?

Well, after checking a few things myself, I wasn't able to sort the fault. Due to the complexity I ended up taking it to a workshop, which determined that the switch controlling the intake manifold was indeed defective. It’s better to have that checked by a professional, since replacing that switch can be a bit tricky, especially if you don't have the right tools or knowledge. Get your error codes read out by a mechanic. If it is that part, the repair cost will probably be around 465€.

Cheers, thanks for the heads-up! I'll book it in for a check-up at the local garage then. Hopefully, it's just that switch and nothing more serious!