P2B34: A Camshaft Profile Actuator B Control Circuit Low Bank 1

On bank 1 the intake camshaft (A) carries a second shifting solenoid, actuator B, which GM's L3B 2.7-litre four labels actuator 2. P2B34 reports a short to ground on its control line: while the driver is switched on, the ECM measures 0.5 Ω or less from signal to ground and stores the fault after 4 failed out of 5 samples at more than 11 V, lighting the MIL at once (Type A). GM bulletin PIT5677, later 21-NA-149, names P2B34 among the codes a damaged engine harness can produce when it rubs through on the camshaft carrier or near the left shock tower; fuses may blow as well. The cam sleeve then cannot be shifted, so the engine runs without lift change or cylinder deactivation. The open circuit has its own code, P2B33.

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, often together with other codes from the same harness section
Lift switching and cylinder deactivation unavailable
With a chafed harness also rough running, reduced power or blown fuses

Most likely causes

Engine harness chafed through on the camshaft carrier or near the left shock tower (GM PIT5677)
Shorted turns or short to housing in actuator B
Oil or moisture in the actuator connector creating a path to ground

What to check, in order

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

Check the oil level and condition before anything else
With the connector unplugged, check whether the signal wire is making contact with ground.
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 P2B34 means

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

Frequently asked questions

Can I keep driving with code P2B34?

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

What causes code P2B34?

The most common causes are: engine harness chafed through on the camshaft carrier or near the left shock tower (GM PIT5677); shorted turns or short to housing in actuator B; oil or moisture in the actuator connector creating a path to ground.

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.