Powertrain, generic (extended)

P25F0 Vacuum Pump Control Circuit B Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P25F0 is stored when the pump's B control circuit reads lower than expected, usually because the switched supply or feedback line is shorted to ground or loaded down by a pump motor with an internal short. A short to ground on the supply side often blows the pump fuse, so the pump then stops altogether. No manufacturer documents P25F0 publicly. Ford's hybrid OBD summary uses a lower limit of 250 mV on the monitoring line for the open-type fault P25EE; a low fault on the same circuit would be judged against a comparable voltage window. The difference from P25EE: there the line is simply without voltage, here the module sees a load or a short pulling it down. CARB lists such outputs among the comprehensive components. Braking assist can fade, and P0556 or P050F may follow.

Likely causes

Chafed supply or feedback wire shorted to ground
Internal short in the vacuum pump motor
Water ingress in the pump connector

Symptoms

  • Hard brake pedal
  • Repeatedly blown vacuum pump fuse
  • Warning lamp on

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€40–650
Time0.5–3 h

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

Parts involved

vacuum pumpwiring harness

Related codes

P25EEP25EFP25F1P258CP050F

References: fordservicecontent.com, law.cornell.edu.