OBD-II code · Powertrain (generic)
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.
Is it safe to drive with P0039?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyWastegate sticking from carbon
- PossibleVacuum/boost line leaking
- PossibleWastegate actuator worn
Symptoms
- Charge status indicator shows fault
- Charging may not start or interrupts
- Slower-than-expected charge rate
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–6 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Wastegate Actuator, Bypass Valve, Boost Pressure Sensor
Related codes
- P00C3Turbocharger/Supercharger Bypass Valve B Control Circuit Range/Performance
- P25FBTurbocharger/Supercharger Bypass Valve C Control Circuit Range/Performance
- P0036HO2S Heater Control Circuit (Bank 1 Sensor 2)
- P0037HO2S Heater Control Circuit Low (Bank 1 Sensor 2)
- P0038HO2S Heater Control Circuit High (Bank 1 Sensor 2)
- P003ATurbocharger/Supercharger Boost Control A Position Exceeded Learning Limit
- P003BTurbocharger/Supercharger Boost Control B Position Exceeded Learning Limit
- P003CA Camshaft Profile Actuator A Control Performance/Stuck Off Bank 1
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.