DTC codes / P25xx · Vehicle speed, idle control and auxiliary inputs / P25AC
P25AC indicates that the engine control module has detected a performance fault in the piston cooling oil control circuit, specifically that the circuit is stuck off when activation is commanded. The computer monitors the oil control solenoid or valve and expects a change in oil flow or pressure when the piston cooling system is energized, but it sees no response, meaning the cooling oil jets are not spraying oil onto the pistons as intended.
Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.
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