P25D1: Exhaust Camshaft Actuator Park Lock Control Circuit Low (Bank 1)

P25D1 indicates that the control signal for the bank 1 exhaust phaser lock is too low, normally a grounded wire or a solenoid winding that leaks to ground. The exhaust side is the hotter one, so insulation that has hardened and cracked near the manifold or turbocharger is a typical finding. With the line grounded, the solenoid may stay powered and keep the pin retracted, or it never gets current, in which case the phaser stays locked. Either way the controller usually stops adjusting exhaust timing and falls back to a safe default. No public manufacturer document lists P25D1; the description follows the J2012 wording, CARB's requirement for circuit checks on output components and the general working of locking cam phasers.

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

Symptoms

• Check engine lamp on
• Exhaust timing fixed, slightly less power

Most likely causes

• Heat-cracked insulation grounding the lock wire
• Shorted exhaust lock solenoid
• Engine oil wicked into the connector

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 P25D1 means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 5: Speed and idle
• D1: Specific fault in that system

Frequently asked questions

Can I keep driving with code P25D1?

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

What causes code P25D1?

The most common causes are: heat-cracked insulation grounding the lock wire; shorted exhaust lock solenoid; engine oil wicked into the connector.

Related codes

• P25D0Exhaust Camshaft Actuator Park Lock Control Circuit/Open (Bank 1)
• P25D2Exhaust Camshaft Actuator Park Lock Control Circuit High (Bank 1)
• P25D4Exhaust Camshaft Actuator Park Lock Control Circuit Low (Bank 2)
• P25CBIntake Camshaft Actuator Park Lock Control Circuit Low (Bank 1)
• P2090"B" Camshaft Position Actuator Control Circuit Low (Bank 1)

Sources

• law.cornell.edu: 13 CCR 1968.2
• en.wikipedia.org: Variable valve timing

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.