Powertrain, generic (extended)

P2B34 A Camshaft Profile Actuator B Control Circuit Low Bank 1

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

On bank 1 the intake camshaft (A) carries a second shifting solenoid, actuator B, which GM's L3B 2.7-litre four labels actuator 2. P2B34 reports a short to ground on its control line: while the driver is switched on, the ECM measures 0.5 Ω or less from signal to ground and stores the fault after 4 failed out of 5 samples at more than 11 V, lighting the MIL at once (Type A). GM bulletin PIT5677, later 21-NA-149, names P2B34 among the codes a damaged engine harness can produce when it rubs through on the camshaft carrier or near the left shock tower; fuses may blow as well. The cam sleeve then cannot be shifted, so the engine runs without lift change or cylinder deactivation. The open circuit has its own code, P2B33.

Likely causes

Engine harness chafed through on the camshaft carrier or near the left shock tower (GM PIT5677)
Shorted turns or short to housing in actuator B
Oil or moisture in the actuator connector creating a path to ground

Symptoms

  • MIL on, often together with other codes from the same harness section
  • Lift switching and cylinder deactivation unavailable
  • With a chafed harness also rough running, reduced power or blown fuses

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

a camshaft profile actuator b b1wiring harnessecm

Related codes

P2B33P2B35P2B37P2B3AP001BP2B53

References: gsi.ext.gm.com, gsi.ext.gm.com, static.nhtsa.gov, static.nhtsa.gov.