P25AB code meaning
Piston Cooling Oil Control Circuit High
Powertrain system Generic code P25xx codes Check engine light
What P25AB means
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.
P25AB at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P25AB
- Check engine lamp after two drives
- Piston cooling jets no longer switched
- Possible reduced engine power
Common causes of P25AB
- Most likelyControl wire pinched against a live supply wire
- PossibleValve side of the circuit shorted to its own supply
- PossibleDamaged or contaminated valve connector
- Less likelyFaulty output stage in the engine control module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Piston cooling solenoidWiring harness
What each part of P25AB means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 5 | Area: vehicle speed, idle control and auxiliary inputs. |
| AB | The exact fault in that area. |
What to do next
- Note P25AB and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P25AB
What does P25AB mean?
P25AB means "Piston Cooling Oil Control Circuit High". P25AB is the counterpart on the supply side: the control line of the piston cooling oil valve is pulled toward battery voltage. It is a generic code, so it means the same on every make.
Is it safe to drive with P25AB?
Drive gently and only to a workshop. With P25AB the car can go into limp mode (reduced power) to protect itself.
Will P25AB fail an emissions test?
Yes, it can. P25AB is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P25AB to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P25AB clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.