P0039 code meaning
Turbocharger/Supercharger Bypass Valve A Control Circuit Range/Performance
Powertrain system Generic code P00xx codes Check engine light
What P0039 means
The turbocharger bypass valve A is the compressor recirculation (diverter) valve: it connects the pressure side of the compressor with the intake side upstream of the turbocharger. It opens when the throttle closes quickly at high boost, so the compressor does not surge and the compressor wheel keeps its speed for the next acceleration. It is not the wastegate, which bypasses exhaust gas around the turbine and has its own codes. The valve is either electric or a vacuum unit controlled by a solenoid. With P0039 the circuit is electrically intact, but the valve does not behave as commanded. On valves with a position sensor, for example, the valve must reach its rest position within a set time after being switched off; the code is set if the measured position deviates too far.
P0039 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2 hours
- Clears after repairAfter a drive cycle
Symptoms of P0039
- Check engine light on
- Fluctuating or too little boost
- Loss of power
- Fluttering noise when lifting off the throttle
Common causes of P0039
- Most likelyValve sticking from carbon or oil mist, or diaphragm torn
- PossibleVacuum line or switching valve leaking (pneumatic design)
- PossiblePosition sensor in the valve faulty
- Less likelyIncreased resistance in the wiring
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Turbocharger bypass valveBypass valve position sensorVacuum lines
What each part of P0039 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 0 | Area: fuel and air metering and auxiliary emission controls. |
| 39 | The exact fault in that area. |
What to do next
- Note P0039 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0039
What does P0039 mean?
P0039 means "Turbocharger/Supercharger Bypass Valve A Control Circuit Range/Performance". The turbocharger bypass valve A is the compressor recirculation (diverter) valve: it connects the pressure side of the compressor with the intake side upstream of the turbocharger. It is a generic code, so it means the same on every make.
Is it safe to drive with P0039?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P0039 fail an emissions test?
Yes, it can. P0039 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0039 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0039 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.