P25DF
A Camshaft Position Control Performance Bank 1
Camshaft phaser A on bank 1 follows the commanded angle too slowly, oscillates, or shows steady-state error outside tolerance. Closed-loop control of cam timing is degraded.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: hard
Symptoms
- Check engine light on
- Power loss especially in mid-rpm range
- Possible rough idle or stalling
- Increased fuel consumption
Common causes
Ordered by how often each turns out to be the cause.
- Oil control valve spool sticks under varnishCommon
- Stretched timing chain shifts cam referencePossible
- Wrong oil viscosity slows phaser responsePossible
Parts involved
- Cam Phaser A B1
- Oil Control Valve
- Cam Position Sensor
P25DF is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.