S90 Hissing Noise Acceleration

That hissing sounds familiar. I had similar symptoms on my old 2014 Opel Insignia diesel – higher fuel consumption, hissing under acceleration, and eventually the check engine light. Does the hissing get louder with more throttle? I'd also check the air intake and the intake manifold.

Yeah, the hissing definitely gets louder when I step on the gas. Where exactly should I be looking on the air intake? Is it something I can check myself, or am I better off taking it in somewhere?

On my Insignia, the problem was a split in the intake hose between the air filter and the turbocharger. It was hard to spot at first. It might be worth a quick look yourself, but if you're not comfortable, or can't find anything obvious, a workshop is probably the best bet. My mechanic charged me around 100€ for the hose and labor.

Thanks a bunch! It was indeed the intake hose. The workshop confirmed the leak and replaced it. Cost me about 100€. Runs like a dream now. I appreciate the help!