walterkeller9

Mercedes C Klasse Hybrid Boost Pressure Issue

My 2019 Mercedes C Klasse hybrid is throwing codes and acting up. Check engine light is on, power is way down, throttle response is laggy. Sometimes it even stalls at idle. Fuel consumption also seems higher and there's this weird whistling/hissing sound when I accelerate. I'm at 64740 km. Could it be a faulty MAP sensor or maybe something with the throttle body? Has anyone else experienced this kind of boost pressure issue?

4 comment(s)

Sounds familiar. I had something similar on my C Klasse. Check the wastegate valve. A defect there could cause those symptoms. Is the whistling noise more like a loud hissing when you accelerate?

Yeah, the whistling is definitely more of a loud hissing under acceleration. So you think it's the wastegate valve? Did you also have reduced engine power and stalling? Was your pressure sensor acting up too?

Yep, reduced power and occasional stalling were part of the package. Never checked the pressure sensor specifically, but a faulty wastegate will mess with the whole boost pressure system. If it's the wastegate, expect a repair bill around 860€. I'd get it checked out by a workshop. Save yourself the headache.

Thanks. Appreciate the insight. Took it to the shop, and you were spot on – wastegate valve was indeed faulty. They replaced it, and everything's back to normal. Cost me exactly 860€. Cheers!

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