Powertrain, generic · Fuel and air metering (injector circuit)

P0240 Turbocharger/Supercharger Boost Sensor B Circuit Range/Performance

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. P0240 is the plausibility fault of sensor B with an electrically valid signal – as with sensor A, compared with barometric and manifold pressure after a stop and with a model while running. A charge air leak on the side or stage of turbo B is a likely cause.

Likely causes

Charge air leak on the side or stage of turbo B
Sensor B dirty or drifting
Contact resistance in the connector
Manifold or barometric sensor faulty

Symptoms

  • Check engine light on
  • Loss of power
  • Uneven boost between the turbos

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

P0241P0242P023EP025FP0236

References: law.cornell.edu, en.wikipedia.org, en.wikipedia.org, fordservicecontent.com.