P0033: Turbo/Super Charger Bypass Valve Control Circuit / Open

P0033 is stored when the ECU detects an open circuit in the control circuit for the turbo or supercharger bypass valve. This valve manages boost pressure by allowing air to bypass the compressor under certain conditions, and the ECU controls it via an electrical signal. An open circuit means the control signal has nowhere to go, so the valve cannot be commanded correctly and the ECU flags the fault.

The open circuit is most often caused by a broken wire in the valve control harness, a disconnected or corroded connector at the valve solenoid, a failed solenoid, or in some cases a fault in the ECU output driver itself. Check the wiring and connectors first, as these are the most likely culprits. Use a multimeter to check for continuity in the circuit from the ECU connector through to the valve solenoid, and measure the solenoid's resistance to see if it is within spec.

At medium severity, P0033 will typically affect boost control behaviour, potentially causing reduced power output or inconsistent boost pressure. While the vehicle may still drive, running a turbocharged engine with a faulty bypass valve can place stress on the forced induction system. Have it diagnosed and repaired at your earliest opportunity rather than letting it sit.