Powertrain, generic (extended)

P25D0 Exhaust Camshaft Actuator Park Lock Control Circuit/Open (Bank 1)

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P25D0 moves the open-circuit lock fault to the exhaust side: the solenoid that releases the locking pin of the bank 1 exhaust cam phaser can no longer be driven because its circuit is interrupted or reads implausibly. The lock keeps the exhaust cam at a defined position while the engine starts, before the phaser has enough oil pressure to hold itself. No manufacturer documents P25D0 publicly; GM's 2015 Volt table names only the intake lock codes, and BorgWarner's mid-position lock for the Hyundai Gamma II four-cylinder is fitted on the intake cam while the exhaust phaser has none. The background therefore rests on CARB's rules for variable valve timing and output circuits. Without lock control the exhaust timing stays fixed, which costs economy and raises emissions.

Likely causes

Open winding in the exhaust phaser lock solenoid
Connector damaged by exhaust heat
Broken wire to the exhaust lock solenoid

Symptoms

  • Check engine lamp on
  • Slightly higher fuel consumption
  • Rough idle possible

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–700
Time0.5–3 h

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

Parts involved

exhaust cam phaser b1park lock solenoidwiring harness

Related codes

P25D1P25D2P25D3P25CAP0013

References: law.cornell.edu, borgwarner.com, en.wikipedia.org.