P2B55: B Camshaft Profile Actuator B Control Stuck On Bank 1

P2B55 flags actuator B on the bank 1 exhaust camshaft as stuck on. Even GM, whose L3B four has a second exhaust actuator and uses P2B51 for it, lists no stuck-on code for that actuator in its 2019 and 2025 tables; no other maker documents P2B55 publicly either. The fault logic can be inferred from the intake twin P2B53: a pin that does not report back to its rest position after shifting. NTN-SNR lists the code as component permanently active, and CARB (e)(13) covers it as a valve control fault. A sleeve held in one exhaust profile changes scavenging and turbo response, and the engine control normally locks out further switching. Related: P2B51 (stuck off), P2B39–P2B3B (circuit).

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 1 is the side of the engine with cylinder 1. Inline engines only have this bank.

Symptoms

Check engine light on
Changed turbo response or reduced power
Possible metallic noise from the camshaft area

Most likely causes

Pin of exhaust actuator B does not retract, often from heat and deposits
Solenoid stays powered because of a wiring or driver fault
Damaged shift groove holds the pin

What to check, in order

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

Check the oil level and condition before anything else
Use the scanner to command the movement and compare the actual position with the requested one.
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 P2B55 means

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

Frequently asked questions

Can I keep driving with code P2B55?

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

What causes code P2B55?

The most common causes are: pin of exhaust actuator B does not retract, often from heat and deposits; solenoid stays powered because of a wiring or driver fault; damaged shift groove holds the pin.

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.