P25ABPiston Cooling Oil Control Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P25AB is the counterpart on the supply side: the control line of the piston cooling oil valve is pulled toward battery voltage. In GM's 18OBDG04 diesel table the check runs while the low-side driver is switched on; if the output then looks tied to power through 0.5 ohm or less, the module counts a short to power, again needing 40 failed samples out of 50 at 100 ms intervals with at least 11 V and logging a Type B fault with the lamp after the second trip. A shorted driver normally switches itself off for protection, so the valve then gets no command at all. Deutz lists P25AB-12 when the valve feeding the piston jets on EMR L1 engines is shorted to battery. Owners mostly notice only the warning lamp; some engines cut power to spare the pistons.
- What you may notice
- Check engine lamp after two drives
- Piston cooling jets no longer switched
- Possible reduced engine power
- Likely causes
- LikelyControl wire pinched against a live supply wire
- PossibleValve side of the circuit shorted to its own supply
- PossibleDamaged or contaminated valve connector
- RareFaulty output stage in the engine control module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.