OBD-II reference

All 9.533 generic OBD-II codes, explained in detail.

Causes, inspection steps and sources — a comprehensive DIY archive. Created and maintained with love for the detail. Good luck and have fun!

Powertrain generic / SAE

P25AD

Piston Cooling Oil Control Circuit Stuck On

The piston cooling solenoid does not close when commanded off — jets remain active when not needed. Oil pressure to top-end consumers may sag, and warm-up takes longer because the cooling jets remove heat from the pistons during cold start.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number5 / AD

Possible causes

  • Solenoid stuck open high
  • Carbon or debris buildup preventing free movement low
  • Component wear with age - mechanical play low

Inspection / repair

  • Difficulty: hard
  • DIY: shop recommended
  • Estimated cost: 300–1500 €
  • Estimated time: 1.5–5 h
  • Component: piston cooling solenoid
  • MIL / check engine light

Sources

References

How to read OBD-II codes

The first letter names the vehicle system, the second digit distinguishes generic from manufacturer-specific, the remaining digits group fault area and number.

PPowertrain: engine, transmission, emissions
BBody: chassis trim, comfort, interior
CChassis: suspension, brakes, steering
UNetwork: CAN, control modules, communication