OBD-II · Engine and powertrain (P)
P0033
Turbo bypass valve A control circuit
What it means
The turbo bypass (diverter/recirculation) valve releases boost when the throttle closes; it is used mainly on turbo petrol engines. The engine computer sees an electrical fault in its control circuit.
Symptoms
- engine warning light
- possible loss of boost or fluttering noise when lifting off
- possibly limp mode
Likely causes, most likely first
| No. | Cause |
|---|---|
| 01 | failed bypass valve coil |
| 02 | unplugged or corroded connector |
| 03 | broken wiring |
What to check, step by step
- 01Inspect the valve connector and wiring.
- 02Measure the valve coil resistance against specification.
- 03Check supply voltage and continuity to the engine computer.
- 04Replace the valve if faulty; also check its diaphragm or piston for leaks.