Espace Hybrid Power Loss Whistling

I had something similar with my Espace. Check the boost pressure sensor and the turbo wastegate actuator. Those are prime suspects for boost control issues.

Could you elaborate on the specifics of your experience? Were the symptoms precisely the same – the whistling, hissing, stalling – or were there variations? Did replacing the boost pressure sensor or wastegate actuator resolve the problem entirely?

Yes, the hissing and power loss were very similar. It ended up being an electrical bypass valve. Definitely get it checked at a workshop.

I appreciate you confirming that you had a similar issue! I followed your advice and had it checked at a workshop. Turns out it was indeed the electrical bypass valve. They replaced it, and the car runs like new again. Thanks!