Powertrain, generic (extended)

P2B50 A Camshaft Profile Actuator B Control Performance/Stuck Off Bank 2

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

Bank 2 of a V-engine has its own intake camshaft (A), and P2B50 reports that the second profile actuator on it does not do its job or stays in the off position. Mercedes-Benz documents the code for the M176 and M177 V8 with CAMTRONIC (for example AMG C63, GLC63 and S 580 models): in topic LI05.20-P-080192 of January 2026, solenoid 2 for the intake side of bank 2 is described as faulty or jammed off, with fault type 07 for a mechanical and 09 for a component fault. Mercedes recommends an engine ECU software update, newer actuator part numbers and an inspection of the harness near the bulkhead, where heat can damage it. The intake lift then cannot switch on that bank. Bank 1 counterpart: P2B4F; stuck on: P2B54.

Likely causes

CAMTRONIC actuator of an older part number, superseded by Mercedes
Engine control software that needs the available update
Harness heat-damaged above the bulkhead near the windscreen
Actuator pin mechanically jammed in the retracted position

Symptoms

  • Check engine light on
  • CAMTRONIC lift switching inactive on bank 2, possibly limp-home mode of the system
  • Slightly uneven running or higher fuel use at part load

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€100–900
Time0.5–3 h

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

Parts involved

a camshaft profile actuator b b2wiring harnessecm

Related codes

P2B4FP2B54P2B52P2B36P003E

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