How do you fix Volvo s80 turbo overboost?

To fix a Volvo S80 turbo overboost, first check for vacuum leaks in the hoses connected to the turbo and wastegate. Inspect the wastegate actuator to ensure it operates correctly; if it's stuck or failing, it may need replacement. Additionally, verify that the boost control solenoid is functioning properly, as a malfunction can lead to incorrect boost levels. If these components are in good condition, consider checking the engine control unit (ECU) for any fault codes or reprogramming needs.