Powertrain, generic (extended)

P2B3B B Camshaft Profile Actuator B Control Circuit High Bank 1

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

For the second exhaust-camshaft profile actuator on bank 1 (camshaft B, actuator B), P2B3B means its control circuit is shorted to a voltage source. GM's L3B strategy checks this with the driver switched off: a resistance of no more than 0.5 Ω between the line and controller power counts as a fault, and four out of five such readings at a supply above 11 V store a Type A code, MIL on at once. Bulletin 21-NA-149, which covers chafed engine harnesses on 2019–2021 Silverado and Sierra 1500 pickups including the L3B, lists P2B3B among the possible codes. The affected exhaust sleeve can no longer be shifted on command, so the valve lift on that side stays as it is. P2B35 is the same fault on the intake side.

Likely causes

Control wire chafed against a live wire in the engine harness
Internal short in exhaust actuator B
Engine module output stage faulty

Symptoms

  • Check engine light comes on during the drive
  • Exhaust lift stays in one profile, cylinder deactivation blocked

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–600
Time1–4 h

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

Parts involved

b camshaft profile actuator b b1wiring harnessecm

Related codes

P2B39P2B3AP2B3EP2B35P002C

References: gsi.ext.gm.com, gsi.ext.gm.com, static.nhtsa.gov, law.cornell.edu.