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.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: hard
Common causes
Ordered by how often each turns out to be the cause.
- Open control wire to the solenoidCommon
- Open solenoid coilPossible
- Pin pushed back out of connector bodyLess likely
Parts involved
- Piston Cooling Solenoid
- Wiring Harness
P25A9 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.