P0242 code meaning
Turbocharger/Supercharger Boost Sensor B Circuit High
Powertrain system Generic code P02xx codes Check engine light
What P0242 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. P0242 means the signal of sensor B is above its upper limit – for sensor A, GM uses 86 % of 5 V and Ford 4.88 V for 5 s. Causes are a short to voltage, an open ground or, on a pulled-up input, an open signal wire.
P0242 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 P0242
- Check engine light on
- Loss of power, limp mode
- Boost B shows its maximum value
Common causes of P0242
- Most likelySensor ground open, or signal wire open on a pulled-up input
- PossibleSignal shorted to 5 V or 12 V
- PossibleSensor faulty internally
- 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 P0242 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). |
| 42 | The exact fault in that area. |
What to do next
- Note P0242 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 P0242
What does P0242 mean?
P0242 means "Turbocharger/Supercharger Boost Sensor B Circuit High". 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 P0242?
Drive gently and only to a workshop. With P0242 the car can go into limp mode (reduced power) to protect itself.
Will P0242 fail an emissions test?
Yes, it can. P0242 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 P0242 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 P0242 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.