Insignia Boost Pressure Problem

Good day. The symptoms you describe are indeed indicative of a boost pressure related fault on your Vauxhall Insignia. The whistling and hissing noises, coupled with reduced power and increased fuel consumption, strongly suggest a leak or a malfunction within the turbocharger system. Given the age and mileage of your vehicle, it would be prudent to examine the wastegate valve for potential defects. Have you checked the readings from the pressure sensor? Are you experiencing turbo lag or unusual acceleration patterns?

Thanks for the quick response. I haven't checked the pressure sensor readings; I don't have the equipment to do that myself, unfortunately. As for turbo lag, yes, definitely. It feels like there's a significant delay before the turbo kicks in, much more so than before. Could a faulty wastegate really cause all these issues?

Affirmative. A defective wastegate valve can indeed manifest all the issues you are currently experiencing. If the wastegate is failing to regulate the boost pressure correctly, it can lead to overboost or underboost conditions, resulting in reduced power, poor engine response, and the noises you described. Considering the complexity of the turbocharger system and your lack of diagnostic equipment, it is my professional recommendation that you take your Vauxhall Insignia to a qualified workshop for a thorough inspection. Ignoring this issue could lead to further damage to the turbocharger or engine.

Thanks, I appreciate the advice. I took it to a local garage, and they confirmed it was indeed a faulty wastegate valve. The repair cost 860€, but the car is now running perfectly again.