Powertrain, generic · Fuel and air metering (injector circuit)
P0242 Turbocharger/Supercharger Boost Sensor B Circuit High
Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible
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.
Likely causes
Sensor ground open, or signal wire open on a pulled-up input
Signal shorted to 5 V or 12 V
Sensor faulty internally
Engine module
Symptoms
- Check engine light on
- Loss of power, limp mode
- Boost B shows its maximum value
Repair estimate
DifficultyEasyDIY possible
Parts and labour€30–250
Time0.5–2 h
Typical range across vehicles; the real cost depends on what the testing finds.
Parts involved
boost pressure sensor bsensor wiringcharge air hoses
Related codes
References: law.cornell.edu, en.wikipedia.org, en.wikipedia.org, fordservicecontent.com.