OBD-II trouble code
P0039: Turbocharger/Supercharger Bypass Valve Control Circuit Range/Performance
Application matters: Identify the actual compressor/supercharger bypass device and full manufacturer DTC. Bypass control, wastegate regulation and boost-pressure sensing are different functions; this label does not select an assembly.
P0039 identifies a bypass-valve range/performance fault. Test the installed control and any required valve response before authorizing wiring, actuator, valve or assembly work.
Quick facts
- System
- Powertrain
- Category
- Fuel & Air
- Severity
- Medium severity
- Driving guidance
- Depends on symptoms and vehicle guidance
- Repair cost range
- Get a vehicle-specific estimate after diagnosis.
- DIY difficulty
- Shop recommended
A code alone cannot establish whether driving is safe. Stop safely for a red brake or oil-pressure warning, overheating, severe misfire, stalling, or impaired braking or steering, and follow the owner's manual. Restraints faults can reduce crash protection even when the vehicle runs normally.
Part of a family with 4 codes
P0039 is one of 4 codes covering boost bypass control faults. The identifier must be matched to the exact vehicle. Related codes can share a diagnostic approach, but their circuit, failure condition, and required tests can differ.
Read the full guide for this family →Browse every code in P0001–P00C6, or start from the full code library.
What does P0039 mean?
P0039 identifies a range/performance result for turbocharger/supercharger bypass-valve control. The monitored response did not fit the operating condition. A plausible value at one moment does not certify a continuously healthy electrical circuit or establish that a diaphragm is torn.
Identify what the actual monitor compares: its command, any feedback and the controlled valve’s result. An electrically driven valve and a vacuum-operated arrangement require different circuit, supply, movement and sealing checks. A position value, pressure change or vacuum loss needs the correct setup and reference before it can identify a failed component.
A charge-path leak, a control problem and a valve fault can produce similar boost complaints. Use the specified tests to separate them. A single commanded response does not verify sealing over every state, and a hold test is valid only at the pressure/vacuum and connections prescribed for the fitted assembly. The code alone is not a turbocharger replacement instruction.
Possible causes
- A bypass valve failing the prescribed movement or sealing checks
- A control, feedback or circuit fault affecting the monitored response
- A vacuum/pressure supply or hose fault on a design that uses it
- Incorrect part, connection or setup following related work
Symptoms
- Check engine light with P0039 stored
- Changed boost response or reduced power depending on the actual fault and control strategy
- Unusual noise on throttle changes where a valve-operation fault produces it
- An intermittent/history code or no obvious driving change
Diagnostic steps
Save the full scan report, code status, and available freeze-frame data before clearing anything. Confirm the reporting module, any failure-type suffix, and the procedure for the exact vehicle. The steps below are an overview; use manufacturer specifications and safety procedures for testing.
- 1.Save the full P0039, any suffix, status and event data. Identify the engine, bypass device and actual monitor before choosing tests.
- 2.Follow the vehicle’s warnings for power loss, unusual noise or unsafe running. Do not accelerate hard to reproduce a boost complaint.
- 3.With ignition off, components cooled and the system isolated as specified, inspect safely accessible connectors and relevant hoses/routing. Do not dismantle a hot or pressurized assembly.
- 4.Have the required supply, return, control and component checks performed at the prescribed points and operating states. Do not apply an unrelated coil band, battery jumper or test lamp to an unfamiliar driver.
- 5.Have the prescribed command/feedback, movement and sealing tests performed using the correct regulated equipment and limits. A failed hold result needs the specified setup; it does not identify every internal failure by itself.
- 6.Repair the demonstrated cause and complete required setup and monitor verification. Use the approved confirmation conditions rather than a generic heavy-load pull or improvised vacuum/pressure test.
Repair cost
Get a vehicle-specific estimate after diagnosis.
A trouble code alone does not price the repair. Ask the shop to identify the confirmed fault and itemize diagnosis, parts, labor, programming or calibration, and taxes.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with check engine light diagnosis preselected. Adjust labor rate and vehicle category to fit your situation.
Related repairs
These links are planning examples; the code does not confirm that any listed part has failed.
DIY vs shop
A qualified shop is recommended because this can involve vehicle-specific boost-system and pressure-input diagnosis, protected electrical or actuator tests, and prescribed cooling or pressure-release precautions when required by the installed system and confirmed repair. Ask the technician what testing confirmed the repair.