Peugeot 508 Engine Power Loss

Whoa, those are some serious symptoms! Sounds eerily familiar to what I went through with my Peugeot 508. Check engine light, power loss, the works! The whistling turning into a hiss is a dead giveaway. Have you checked the intercooler pipes or the throttle body for any leaks or damage? It could also be the MAP sensor acting up. I was chasing turbo lag like crazy before figuring out the issue.

Interesting, thanks for your input! I was mainly suspecting the wastegate valve. Regarding the intercooler pipes and throttle body, are there any specific areas I should focus on when inspecting them? Also, could a faulty MAP sensor really cause such a dramatic loss of power and the stalling issue?

Absolutely, a faulty MAP sensor can wreak havoc! It's like the brain getting bad intel. As for the intercooler pipes and throttle body, check all the connections and seams first. Look for any oily residue, which is a sign of a leak. Given the loud hissing, it's probably a decent-sized leak. To be honest, with all those symptoms combined, it's probably more than just a simple fix. I'd recommend getting it properly diagnosed at a workshop to pinpoint the exact culprit before throwing parts at it. Might save you some headaches and money in the long run.

Thanks a lot for sharing your experience and insights! I appreciate the advice. I took it to the workshop, and it turned out to be indeed the wastegate valve. They replaced it, and the total repair cost came to 860€. Now, the Peugeot runs smoothly again.