Fiat Bravo boost pressure fault

Hey! Those symptoms definitely point towards a boost issue. A faulty pressure sensor could be the culprit, but it could also be a vacuum leak somewhere. Has the car been sitting for a while, or have you noticed any hissing sounds? Turbo lag can also be a symptom. Do you have any way to check the actual boost pressure? A cheap OBD2 reader would be helpful.

Thanks for the quick response. I haven't detected any hissing sounds, but the engine's performance has degraded gradually. Could you elaborate on how a vacuum leak could manifest, and where I should look?

Okay, gradual degradation points away from a sudden hose failure. The turbo needs a vacuum to control the amount of boost it's producing. If there's a leak, the turbo can't regulate the pressure properly, leading to over- or under-boosting. Common culprits are the vacuum lines running to the boost controller, sometimes called a vacuum switching valve. It's tricky to pinpoint without proper equipment. Given the symptoms, it might be best to take it to a workshop to get it properly diagnosed.

I followed your advice and took the vehicle to a workshop. The diagnosis confirmed a defect in the vacuum switching valve, which was replaced. The total cost was 140€. The engine performance has now returned to normal. Thanks again for your help!