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

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.

Medium severity. Can I keep driving?Drive little and gently. If you hear timing chain noise or the oil light comes on, shut off the engine.

Bank 2 is the side without cylinder 1, so it only exists on V or boxer engines.

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

Most 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CAMTRONIC actuator of an older part number, superseded by Mercedes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

What to check, in order

Start with the simplest. You can tick off each step.

Check the oil level and condition before anything else
Compare the reading with other engine data while varying the engine speed.
Check the solenoid valve's connector
Compare commanded and actual angles in live data
Test the solenoid valve and its filter, if it has one
Check the engine timing if there is chain noise

Good to know

Repair difficulty: medium
It can trigger limp mode.
It affects emissions.

What each character of P2B50 means

P: Powertrain: engine and transmission
2: Generic code: same on every make
B: Subsystem depends on the code range
50: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2B50?

Drive little and gently. If you hear timing chain noise or the oil light comes on, shut off the engine.

What causes code P2B50?

The most common causes are: cAMTRONIC actuator of an older part number, superseded by Mercedes; engine control software that needs the available update; harness heat-damaged above the bulkhead near the windscreen.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.