OBD-II code · Powertrain (generic, extended)
P25A9 Piston Cooling Oil Control Circuit/Open
The piston-cooling oil-jet control circuit is open. Modern engines with under-piston oil jets switch them on under high load to cool the piston crown — controlled by a solenoid valve in the oil gallery. With the circuit broken, jets cannot be commanded on or stay locked off, raising piston temperatures under load.
Is it safe to drive with P25A9?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelyOpen control wire to the solenoid
- PossibleOpen solenoid coil
- Less likelyPin pushed back out of connector body
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–4 h
- Emissions test
- Usually unaffected
- Parts involved
- Piston Cooling Solenoid, Wiring Harness
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.