Mini One boost pressure actuator fault

I experienced a similar issue with my Mini Cooper. Check engine light, reduced power, and a noticeable whistling sound pointed towards a boost leak. In my case, it was a faulty actuator valve. Have you checked the pressure sensor readings? A diagnostic scan should reveal if the boost pressure is within the specified range or if it's fluctuating erratically. Also, inspect the hoses connected to the turbocharger for any signs of cracks or damage. A leak there can also cause similar symptoms.

Could you elaborate on the pressure sensor readings you observed? Specifically, what values indicated the actuator valve failure?

The pressure sensor was reporting values outside the normal operating range, even at idle. During acceleration, the boost pressure was significantly lower than expected, indicating a failure of the actuator to properly regulate the airflow. The diagnostic tool specifically flagged an issue with the turbo actuator. Given your symptoms, it is highly probable that you have a similar failure. I advise you to get a diagnostic at your local workshop.

I appreciate the insights. The electrical bypass valve was indeed defective. The turbo actuator was replaced, and the boost pressure is now within the expected range. Total cost was 250€. Thank you.