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.

Likely causes

Symptoms

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

Repair estimate

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

Related codes

References: gsi.ext.gm.com, law.cornell.edu, borgwarner.com.