P0039 — Turbocharger/Supercharger Bypass Valve A Control Circuit Range/Performance
The wastegate or bypass valve A on the turbo/supercharger does not respond mechanically as expected to its control signal. Boost pressure deviates from target.
General code reference. Confirm the definition and diagnostic procedure for your vehicle's year, model and engine. A stored code alone does not identify a failed part.
Affected components
- Wastegate actuator
- Bypass valve
- Boost pressure sensor
Possible causes to check
These are possible checks, not a ranked diagnosis. Follow the vehicle manufacturer's test procedure before replacing parts.
- Wastegate sticking from carbon
- Vacuum/boost line leaking
- Wastegate actuator worn
Possible symptoms
- Charge status indicator shows fault
- Charging may not start or interrupts
- Slower-than-expected charge rate
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
- A drive cycle may be required after repair
- Reduced-power or limp mode may occur
Related codes
Sources
Check each reference's vehicle and model-year scope. General background links do not establish which fault is most likely on your vehicle.
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.