P2B39: B Camshaft Profile Actuator B Control Circuit/Open Bank 1

Camshaft B is the exhaust camshaft, and actuator B is the second shifting solenoid on it. On GM's 2.7-litre L3B the exhaust side has only two such actuators, so this is the last of them; GM's tables call it exhaust camshaft profile actuator 2. P2B39 flags an open control circuit: with the output commanded on, the ECM reads an impedance of at least 200 kΩ to ground. It needs 4 failures in 5 samples, a supply above 11 V and key in crank or run, and it turns the MIL on in the first trip. A loose connector on the camshaft carrier, a broken wire or an open coil are the usual causes. The exhaust sleeve then stays put, so the engine cannot change profile on that side. The intake counterpart is 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 in the first drive
Exhaust lift profile no longer switches, cylinder deactivation unavailable

Most likely causes

Exhaust actuator connector loose or corroded on the camshaft carrier
Broken wire in the engine harness
Open solenoid coil in exhaust actuator B

What to check, in order

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

Check the oil level and condition before anything else
Check the continuity of the wire between the component and the control module.
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 P2B39 means

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

Frequently asked questions

Can I keep driving with code P2B39?

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

What causes code P2B39?

The most common causes are: exhaust actuator connector loose or corroded on the camshaft carrier; broken wire in the engine harness; open solenoid coil in exhaust actuator B.

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.