theresaschulze1

Seat Mii Turbo Issues Check Engine Light and Power Loss

Alright, I'm officially stumped. My Seat Mii built in 2019 with a gasoline engine is giving me fits at 151671 km. The check engine light is on, and I'm experiencing reduced engine power, a delay in engine response, and a weird whistling noise that turns into a loud hiss when accelerating. Sometimes the engine even stalls at idle, and my fuel consumption has definitely gone up. I suspect a boost leak somewhere, but I'm not sure where to start digging. From what I've read, a defective electrical bypass valve could be the issue. Anyone else experienced anything similar with their turbo system?

A 2019 Seat Mii with a gasoline engine is experiencing issues such as a check engine light, reduced power, delayed engine response, increased fuel consumption, and a whistling noise that turns into a hiss during acceleration. The suspected cause is a boost leak, potentially due to a defective electrical bypass valve. A similar issue was resolved by replacing the electrical bypass valve, which restored normal engine function and eliminated the check engine light and unusual noises.

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4 comment(s)

Whoa, sounds rough! I had a similar issue with my Seat Mii a while back. Check Engine Light, plus a really noticeable loss of power. The culprit? A dodgy turbo actuator valve. Have you checked that?

Thanks for the quick reply! When you say "dodgy turbo actuator valve", are you referring to the actual actuator valve itself, or could it also be related to the pressure sensor giving false readings? Also, did you notice any specific whistling or hissing noises?

Yep, I mean the actuator valve itself. I didn't check the pressure sensor, to be honest. Just took it to the shop. And yes, there was a definite whistling sound, especially under acceleration. A boost leak will definitely cause those symptoms. Get it checked out soon before it causes further damage to the turbo!

Just wanted to close the loop. You were spot on! Turns out it was indeed the electrical bypass valve. Got it replaced, and the Mii is running like new again. The check engine light is gone, power is back, and no more weird noises. Cost me 250€ all in. Thanks a bunch for your help!

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SEAT

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MII