Powertrain, generic (extended)

P2B4C B Camshaft Position Actuator Position Sensor B Range/Performance Bank 2

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P2B4C stands for an implausible but electrically valid signal from the B sensor watching the exhaust actuator of bank 2. It is the exhaust-side mirror of P2B44, which Mercedes-Benz documents on CAMTRONIC V8s (M176/M177) for intake solenoid 2 of bank 2; for P2B4C itself there is no public manufacturer text. In the same bulletin Mercedes reports the exhaust sensor of solenoid 1 on bank 2 as P34C1 and points to engine software and revised actuator part numbers. CARB names a lift-mechanism pin that never arrives where it should as a failure the OBD system must find, which is what this feedback check exists for. Sticking pins and deposits are therefore the main suspects. Bank 1 counterpart: P2B48.

Likely causes

Exhaust actuator pin sticking (deposits, wear)
Engine control software outdated
Intermittent contact in the sensor signal

Symptoms

  • Check engine light on
  • Lift system or cylinder deactivation in limp-home
  • Higher part-load consumption

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–900
Time1–4 h

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

Parts involved

b camshaft position actuator pos sensor b b2wiring harnessecm

Related codes

P2B44P2B48P2B4BP2B4DP2B4EP34C1

References: law.cornell.edu, ntn-snr.com, static.nhtsa.gov.