P0239 code meaning
Turbocharger/Supercharger Boost Sensor B Circuit
Powertrain system Generic code P02xx codes Check engine light
What P0239 means
Boost sensor B is a second boost pressure sensor, for a second turbo or bank on parallel twin-turbo engines or a second stage on two-stage systems. No manufacturer using sensor B codes was found – GM, Ford and Saab, even on two-stage and twin-turbo engines, use a single boost sensor; the description follows CARB and the documented sensor A codes. P0239 is the general circuit fault of sensor B, the counterpart of P0235, without telling low, high or range apart. As with sensor A, boost control would be switched off, with loss of power.
P0239 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyEasy, DIY possible
- Typical labor0.5 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0239
- Check engine light on
- Loss of power, limp mode
- Uneven boost build-up on twin turbos
Common causes of P0239
- Most likelyConnector or wire to sensor B open or corroded
- PossibleSensor B faulty or oily
- Less likelyShared 5 V reference or ground disturbed
- Less likelyEngine module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Boost pressure sensor bSensor wiringCharge air hoses
What each part of P0239 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 2 | Area: fuel and air metering (injector circuit). |
| 39 | The exact fault in that area. |
What to do next
- Note P0239 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 P0239
What does P0239 mean?
P0239 means "Turbocharger/Supercharger Boost Sensor B Circuit". Boost sensor B is a second boost pressure sensor, for a second turbo or bank on parallel twin-turbo engines or a second stage on two-stage systems. It is a generic code, so it means the same on every make.
Is it safe to drive with P0239?
Drive gently and only to a workshop. With P0239 the car can go into limp mode (reduced power) to protect itself.
Will P0239 fail an emissions test?
Yes, it can. P0239 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 P0239 to fix?
Difficulty: easy. A typical repair takes 0.5 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0239 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.