Powertrain, generic (extended)

P25AE Piston Cooling Oil Pressure Too Low

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P25AE means the oil pressure reaching the piston cooling jets is below what the engine controller requires, even though the valve circuit itself shows no electrical fault. Volvo and Mack heavy trucks store it as P25AE00. Their bulletins KC-170 (2020, reissued 2021) and CBR 170-8 (May 2025, Mack and Volvo chassis from 2007 onward) cover an inactive P25AE00 set after a hard pull when engine oil pressure briefly drops, with SPN 4811 and SPN 100 named as related. Before parts are swapped, the oil temperature reading is compared with an infrared thermometer; a gap above 5 °F means a new sensor, otherwise technical support takes over. Real causes include low oil level, a tired pump or blocked jets. Lasting low cooling pressure endangers the pistons, so engines may derate.

Likely causes

Low oil level or oil starvation under hard load
Oil temperature sensor reading wrong (Volvo/Mack bulletin)
Worn oil pump or leaking pressure relief valve
Clogged oil filter or piston cooling jets

Symptoms

  • Inactive code after heavy pulling
  • Low oil pressure warning at the same time
  • Engine derate possible

Repair estimate

DifficultyHardWorkshop job
Parts and labour€50–2,500
Time0.5–8 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

oil pumpoil gallerypiston cooling solenoid

Related codes

P25ACP25A9P0520P0524

References: static.nhtsa.gov, static.nhtsa.gov, law.cornell.edu.