P0033

Universal

Turbo/Super Charger Bypass Valve Control Circuit / Open

Definition source: General OBD-II reference catalog

Definition verification: Not independently verified for display.

Time: Varies by diagnosis and vehicle | Diagnostic difficulty: Medium

Medium Severity

The engine computer has detected an open or interrupted electrical circuit in the control system for the turbocharger or supercharger bypass valve. That valve helps manage airflow or boost, so the fault may affect engine power or boost response. The code identifies a detected circuit condition; it does not by itself prove the valve needs replacement. Exact system design and procedures depend on the vehicle.

Report an error with this code

⚠️ Before You Begin (Safety First)

If the vehicle loses power, runs poorly, or cannot maintain a safe speed, pull over when safe and arrange assistance. Avoid hard acceleration until the fault is diagnosed. Stop driving if there are severe drivability problems or other warning signs, such as unusual smoke or overheating.

Common Symptoms

The check-engine light may be on because the engine computer has detected an open bypass-valve control circuit.
Reduced power or weak boost response may occur if the bypass valve cannot be controlled as intended.
Acceleration may feel inconsistent if airflow or boost management is affected.
There may be no obvious driving symptoms if the fault has little effect under current operating conditions.

Common Causes

A damaged, disconnected, or corroded connector may interrupt the valve control circuit.
Wiring may be broken, chafed, or otherwise damaged, creating an open circuit.
The bypass valve actuator or its electrical component may have an internal fault.
A fuse or other circuit supply issue may interrupt operation, where applicable to the vehicle design.
A fault in the circuit's control electronics is possible and should be considered only after the wiring and actuator are checked.
A mechanically sticking valve may affect operation, though this code describes a control-circuit condition and does not establish a mechanical failure.

Diagnostic Steps

Record the code and any other stored codes before clearing anything; related codes and scan information can help guide diagnosis.
With the engine off and cool, visually inspect accessible wiring and connectors at the bypass-valve system for disconnection, damage, corrosion, or rubbing.
Check the vehicle owner's manual for any relevant fuse and inspect it only if the manual identifies one for this system; replace it only with the specified type and rating.
Do not force the valve or probe terminals without the correct service information and tools; incorrect testing can damage components.
If the wiring looks intact or the code returns, have the circuit and actuator tested using vehicle-specific procedures.

When to Call a Professional

A technician can check stored codes and scan data, inspect the bypass valve circuit and connectors, and test circuit continuity, power, ground, and control operation using vehicle-specific service information. The valve actuator and wiring should be evaluated before replacing parts; exact test points and procedures vary by vehicle.

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Commonly Asked Questions

Does P0033 prove the bypass valve is bad?

No. It reports an open condition in the valve control circuit. Wiring, connectors, circuit supply, the actuator, or control electronics may need to be checked before identifying the cause.

Can I drive with P0033?

If the vehicle runs normally, a cautious trip for diagnosis may be possible, but avoid hard acceleration. If power loss or poor running makes driving unsafe, stop when safe and arrange assistance.

What does the bypass valve do?

Depending on the system design, it helps manage airflow or boost through or around the turbocharger or supercharger. The engine computer controls it as part of engine operation.

Why might there be no symptoms?

The effect can depend on when the valve is needed and how the vehicle responds to the fault. The warning light may be the only noticeable sign.

What should be checked before replacing a part?

Inspect connectors and wiring, review related codes and scan data, and test the circuit and actuator according to service information for the vehicle's model, year, and engine.

Browse Available Code Guides

Previous and next available guides in database record order, across makes. Adjacent entries may share a code number and do not necessarily describe related faults.