Laguna turbo whistling noise power loss

Sounds rough! I had something similar happen with my old Volvo V70 – a diesel, though. Check engine light, power loss, weird noises... turned out to be a faulty electrical bypass valve causing a boost leak in the turbo system. I'd be looking at the turbo actuator, boost control, and any related hoses for leaks. Could also be the actuator valve itself. Any codes being thrown?

Boost leak, huh? That's interesting. So, when you say 'electrical bypass valve,' are we talking about the same thing as the turbo actuator? 'Cause that's what I'm leaning towards. And how obvious was the leak on your Volvo? Like, could you pinpoint it easily, or was it more of a 'general area of suspicion' type of thing?

Well, I'm no mechanic, but from what I remember, the bypass valve and the actuator are closely linked in controlling the boost. It's all part of the turbocharger system. On the Volvo, the leak wasn't super obvious at first. It was more of a general area – we suspected a hose, but eventually, the mechanic found the valve itself was defective. Honestly, with all your symptoms, I'd bite the bullet and take it to a reputable workshop.

Appreciate the input! I was hoping it'd be something simple, but a trip to the shop sounds inevitable. Turns out you were spot on about the bypass valve! Got it sorted at the local garage. The Electrical bypass valve was indeed defective. 250€ later and it runs like new! Cheers!