Powertrain, generic (extended)

P2B4E B Camshaft Position Actuator Position Sensor B Circuit High Bank 2

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2B4E closes the group: the exhaust-side position sensor B of bank 2 sends a signal above its upper limit. Usually the sensor ground is open, the signal line is shorted to a supply, or the sensor is faulty. No manufacturer explains P2B4E publicly; the NTN-SNR code list only gives outlet sensor B, second bank, signal too high. In the CAMTRONIC family Mercedes uses on the M176/M177, the sensor is part of the actuator, so a confirmed sensor fault means a new actuator. Until then the engine runs on the fixed default cam profile on that bank, which mostly shows as a lit warning lamp and slightly more fuel use. CARB requires such circuit faults to be detected. Bank 1 counterpart: P2B4A.

Likely causes

Sensor ground open
Signal line shorted to a supply
Sensor faulty (actuator replacement)

Symptoms

  • Check engine light on
  • Bank 2 runs on the default cam profile
  • Slightly higher fuel use

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–650
Time0.5–3.5 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

P2B46P2B4AP2B4BP2B4CP2B4DP34C3

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