Powertrain, generic (extended)

P2C2A Turbocharger/Supercharger Bypass Valve B Position Sensor Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2C2A covers an open or otherwise unreadable position feedback from compressor bypass valve B, the electrically positioned recirculation valve of the second charger. Without a valid feedback the engine module cannot confirm how far the valve has opened, which an Achates Power patent names as the reason such sensors are monitored. No manufacturer documents P2C2A publicly. GM's 2019 tables describe the A-side sensor of the supercharged LT5 as a ratiometric signal relative to the 5 V reference, but publish only its low and high codes P2BBC/P2BBD. GM defines charger A as bank 1 in parallel layouts and first in exhaust flow in series layouts, so B is the other one. Wiring and connectors near the hot charger are the usual suspects; boost is often limited.

Likely causes

Unplugged, loose or corroded connector at valve B
Broken signal, reference or ground wire of the sensor
Internal open in the position sensor of the actuator

Symptoms

  • Check engine light
  • Boost limited, less power

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 bwiring harnessecm

Related codes

P2C2BP2C2CP2C29P2BBBU066BP00C0

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