Turbocharger/Supercharger "A" Overboost Condition
The turbocharger compresses the air going into the engine to give it more power; the engine computer regulates that boost pressure with the wastegate or the turbo's vanes. This code means the actual pressure clearly exceeds what the engine computer asks for.
What the car has detected
The measured boost pressure has exceeded the target by more than the allowed margin for over a second.
Drive gently and have it checked soon: too much boost puts more stress on the engine than intended and the engine computer may limit power to protect it.
Symptoms
- Engine warning light on
- Surging or a brief burst of extra power
- Loss of power or limp mode when the engine computer limits it
- Uneven running when accelerating
Possible causes
- Wastegate that won't open or is seized
- Faulty or stuck turbo control valve
- Vacuum or control lines misconnected, loose or blocked
- Boost pressure sensor reading wrong
- Seized turbo or turbo vanes
Checks for the garage
- Read the freeze frame data and compare actual with requested boost
- At rest, check the boost sensor reads the same as atmospheric pressure
- Check the vacuum and control lines are properly connected and unblocked
- Activate the control valve with diagnostics and check the wastegate moves and opens
- Check the turbo if everything above is fine
Next step
Avoid full throttle and have the wastegate, the turbo control valve and the pressure sensor checked.
Go to a garage soon; don't push the engine until it has been checked. Checking turbo regulation needs diagnostics.