P2B4F: A Camshaft Profile Actuator B Control Performance/Stuck Off Bank 1

P2B4F covers the second profile actuator (B) on the intake camshaft of bank 1, a solenoid whose pin engages a groove on a sliding cam sleeve to change valve lift. Despite the title wording, GM's L3B 2.7-litre four (19OBDG03D, again in 25OBDG03B) uses it for the reverse case: a Hall element reports three pin states (extending 55, extended 45, retracted 68), and if the signal falls below 55 although no shift was commanded, the pin has fired on its own. Four wrong readings in five cylinder events with the engine running and more than 11 V set a Type A fault, MIL at once. The supplier NTN-SNR lists the code as actuator never active. A pin stuck out on the same actuator is P2B53; wiring faults sit under P2B33–P2B35.

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

MIL on in the first drive with the fault
Intake lift switching locked out, less pull or higher consumption
Cylinder deactivation no longer available

Most likely causes

Actuator B pin extends without a command (sticking solenoid, weak return spring)
Hall feedback of the actuator delivers wrong pin states
Shift groove on the cam sleeve worn so the pin is dragged out

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 P2B4F means

P: Powertrain: engine and transmission
2: Generic code: same on every make
B: Subsystem depends on the code range
4F: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2B4F?

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

What causes code P2B4F?

The most common causes are: actuator B pin extends without a command (sticking solenoid, weak return spring); hall feedback of the actuator delivers wrong pin states; shift groove on the cam sleeve worn so the pin is dragged out.

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.