Powertrain, generic (extended)

P2B4F A Camshaft Profile Actuator B Control Performance/Stuck Off Bank 1

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2B4F covers the second profile actuator (B) on the intake camshaft of bank 1, a solenoid whose pin engages a groove on a sliding cam sleeve to change valve lift. Despite the title wording, GM's L3B 2.7-litre four (19OBDG03D, again in 25OBDG03B) uses it for the reverse case: a Hall element reports three pin states (extending 55, extended 45, retracted 68), and if the signal falls below 55 although no shift was commanded, the pin has fired on its own. Four wrong readings in five cylinder events with the engine running and more than 11 V set a Type A fault, MIL at once. The supplier NTN-SNR lists the code as actuator never active. A pin stuck out on the same actuator is P2B53; wiring faults sit under P2B33–P2B35.

Likely causes

Actuator B pin extends without a command (sticking solenoid, weak return spring)
Hall feedback of the actuator delivers wrong pin states
Shift groove on the cam sleeve worn so the pin is dragged out

Symptoms

  • MIL on in the first drive with the fault
  • Intake lift switching locked out, less pull or higher consumption
  • Cylinder deactivation no longer available

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–700
Time0.5–3 h

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

Parts involved

a camshaft profile actuator b b1wiring harnessecm

Related codes

P2B53P2B50P2B51P2B33P003C

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