Powertrain, generic (extended)

P2B55 B Camshaft Profile Actuator B Control Stuck On Bank 1

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2B55 flags actuator B on the bank 1 exhaust camshaft as stuck on. Even GM, whose L3B four has a second exhaust actuator and uses P2B51 for it, lists no stuck-on code for that actuator in its 2019 and 2025 tables; no other maker documents P2B55 publicly either. The fault logic can be inferred from the intake twin P2B53: a pin that does not report back to its rest position after shifting. NTN-SNR lists the code as component permanently active, and CARB (e)(13) covers it as a valve control fault. A sleeve held in one exhaust profile changes scavenging and turbo response, and the engine control normally locks out further switching. Related: P2B51 (stuck off), P2B39–P2B3B (circuit).

Likely causes

Pin of exhaust actuator B does not retract, often from heat and deposits
Solenoid stays powered because of a wiring or driver fault
Damaged shift groove holds the pin

Symptoms

  • Check engine light on
  • Changed turbo response or reduced power
  • Possible metallic noise from the camshaft area

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–800
Time0.5–3 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

P2B51P2B53P2B56P2B3AP005B

References: ntn-snr.com, law.cornell.edu, gsi.ext.gm.com.