P25CB: Intake Camshaft Actuator Park Lock Control Circuit Low (Bank 1)

P25CB points to a control line for the intake phaser lock on bank 1 that reads lower than it should, most often a short to ground on the wire or inside the lock solenoid. Depending on how the driver is wired, the solenoid may then stay energised or never receive current, so the lock pin is either released all the time or cannot be pulled back. Released permanently, the phaser can rattle at start before oil pressure arrives; stuck in, it keeps the intake cam at its base timing. GM's 2015 Volt and ELR OBD table 15OBDG01 places P25CB in the intake phaser fault bundles that pause the related phaser checks, without listing a threshold. CARB requires circuit checks on such output components. Low voltage events can set several lock codes together.

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

Symptoms

• Check engine lamp on
• Brief rattle from the timing drive at start
• Reduced power with fixed intake timing

Most likely causes

• Lock control wire shorted to ground
• Internal short in the lock solenoid
• Weak battery or voltage dip during cranking

What to check, in order

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

1. Check the oil level and condition before anything else
2. With the connector unplugged, check whether the signal wire is making contact with ground.
3. Check the solenoid valve's connector
4. Compare commanded and actual angles in live data
5. Test the solenoid valve and its filter, if it has one
6. 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 P25CB means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 5: Speed and idle
• CB: Specific fault in that system

Frequently asked questions

Can I keep driving with code P25CB?

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

What causes code P25CB?

The most common causes are: lock control wire shorted to ground; internal short in the lock solenoid; weak battery or voltage dip during cranking.

Related codes

• P25CAIntake Camshaft Actuator Park Lock Control Circuit/Open (Bank 1)
• P25CCIntake Camshaft Actuator Park Lock Control Circuit High (Bank 1)
• P25CEIntake Camshaft Actuator Park Lock Control Circuit Low (Bank 2)
• P25D1Exhaust Camshaft Actuator Park Lock Control Circuit Low (Bank 1)
• P2088"A" Camshaft Position Actuator Control Circuit Low (Bank 1)

Sources

• gsi.ext.gm.com: 15OBDG01 Hybrid Diagnostics
• law.cornell.edu: 13 CCR 1968.2
• borgwarner.com: borgwarner s vct technology with mid position lock

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.