Powertrain, generic (extended)

P2BBF Turbocharger/Supercharger Bypass Valve A Supply Voltage Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2BBF concerns the power side of bypass valve A rather than its position feedback. Electric recirculation valves are moved by a small DC motor fed through an H-bridge in the engine module, and the bridge chip itself flags when its supply drops too far. GM documents exactly this for the eCRV of the 2019 Corvette ZR1: the motor driver reports low voltage in 80 of 100 samples at 12.5 ms, with relay voltage at least 11 V and the engine not cranking; Type A, MIL at once. Data sheets for throttle-type H-bridges such as NXP's MC33926 show how such an output stage switches off below its undervoltage lockout and reports this on a status line. Causes are a weak feed, a poor module ground or connector, or an internal driver fault. Without drive power the valve stays where it last stopped.

Likely causes

High resistance in the engine module feed, fuse or ground connection
Weak battery or charging fault causing voltage dips
Corroded pins at the engine module or valve connector
Internal fault of the H-bridge driver in the engine module

Symptoms

  • Check engine light on immediately
  • Valve no longer moves, boost limited or surging on lift-off
  • Often accompanied by other low-voltage codes

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€40–1,200
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

P2BC0P0033P0034P0035P2C2E

References: law.cornell.edu, gsi.ext.gm.com, nxp.com.