Peugeot 308 Jerking Whistling Hissing

While I don't have experience with the Peugeot 308 specifically, I encountered similar symptoms with my old Opel Astra – engine light, power loss, and a strange whistling. In my case, it turned out to be a leak in the air intake system. Could you elaborate on what you have already checked in relation to the intake manifold and the turbo boost?

You mention a leak in the air intake system. Was it obvious when you found it, like a split hose, or something more subtle? And where exactly was the leak located? I've visually inspected the hoses, but nothing jumps out.

It was not immediately apparent. The leak manifested as a hairline crack within a convoluted section of the intake hosing, thus requiring a thorough physical manipulation of the component to expose it. If your preliminary inspection yields inconclusive results, I would suggest entrusting the issue to a qualified workshop for a comprehensive diagnostic assessment.

Thanks for the advice. I took it to the shop, and you were spot on! The cable for the boost pressure sensor was indeed defective, causing a bad connection. Replaced it, and everything's back to normal. Total cost was 95€ Appreciate the help!