Seat Exeo boost pressure issue

I am sorry to hear about the troubles you are experiencing with your Seat Exeo. Your symptoms do sound rather unpleasant. Funnily enough, I had a similar issue with my old Renault Megane, although it was a diesel. Check engine light, reduced power, and a strange whistling noise all pointed to a boost leak. Is it possible the actuator valve is faulty and causing the turbo wastegate to malfunction? Have you had the chance to inspect the hoses for any obvious signs of damage?

Thank you for your swift response. I appreciate you sharing your experience with the Renault Megane. When you say 'inspect the hoses', could you perhaps elaborate on which specific hoses I should be focusing on? Also, what exactly should I be looking for in terms of 'obvious signs of damage'? Would a simple visual inspection suffice, or would more specialized equipment be required?

As for the hoses, focus on those connected to the turbo and intercooler. Obvious signs of damage might include cracks, splits, or even loose connections. A visual inspection should be sufficient to identify any major issues. However, bear in mind that diagnosing turbo issues without proper tools and expertise can be challenging. Considering the range of symptoms you are experiencing, and with the potential of the hissing noise and stalling, it would probably be prudent to consult a qualified mechanic. They can perform a thorough diagnosis and pinpoint the exact cause of the boost pressure actuator fault. I think that would be a good starting point.

I sincerely appreciate you taking the time to share your experience. It seems my suspicions were indeed correct. I took it to a trusted workshop, and after a thorough inspection, they confirmed the electrical bypass valve was defective, causing the boost pressure actuator fault. They replaced it, and the car is now running smoothly again. The repair cost me approximately 250€. I am glad it is resolved now. Thank you again for your help!