Powertrain, generic (extended)

P2BBD Turbocharger/Supercharger Bypass Valve A Position Sensor Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2BBD is the high-side counterpart: the position signal from bypass valve A rises toward the full reference voltage. That points to a short to the 5 V supply or to battery voltage, a broken sensor ground – the signal then floats upward – or a defective sensor. On GM's 2019 Corvette ZR1 with the LT5 V8 the module flags a raw position reading above 95 % of reference in 10 out of 14 samples at 100 ms intervals, with at least 11 V on the powertrain relay and outside of cranking; Type A, so the MIL lights at once. P2BBC covers the low side and P2BBB a general circuit fault of the same sensor. With the reading implausible, the module usually holds the valve in a safe position and reduces boost, so the car feels flat and may make noise when the throttle snaps shut.

Likely causes

Open sensor ground wire or corroded ground terminal
Signal wire shorted to the 5 V reference or to battery voltage
Defective position sensor in the valve actuator
Moisture in the valve connector creating a leakage path

Symptoms

  • Check engine light on immediately
  • Reduced power because boost is limited
  • Unusual noise when lifting off the throttle

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–900
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

turbo bypass valve awiring harnessecm

Related codes

P2BBBP2BBCP2BBEP23AAP2C2C

References: law.cornell.edu, gsi.ext.gm.com, patents.google.com.