Powertrain, generic (extended)

P25FF Electrical System Voltage Stabilizer Control Module Performance

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

P25FF reports that the module which steadies the 12 V supply for sensitive electronics does not work as intended. Such stabilizers mainly appear on cars with automatic engine stop/start: every restart drags the battery voltage down hard, according to a semiconductor maker briefly below 4 V, which would otherwise reset radios, displays and similar loads. A DC/DC stage raises the voltage for those moments. No manufacturer publicly documents P25FF itself. GM's 2017 Chevrolet Malibu illustrates the circuit in practice: current fed back through the OnStar backup battery wiring into the DC-DC converter inhibited stop/start and lit the MIL, cured by removing a single fuse, without a code being named. Usually stop/start stays disabled and screens may reboot on restart; the engine keeps running normally.

Likely causes

Internal fault in the voltage stabilizer or DC/DC converter module
Aged or wrong-type 12 V battery so the module cannot hold the voltage
Current backfeed or poor supply/ground connection at the module

Symptoms

  • Automatic stop/start no longer active
  • Radio or display resets when the engine restarts
  • Warning light depending on the maker

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–600
Time0.5–2 h

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

Parts involved

voltage stabilizer moduledc dc converter

Related codes

P0560P0561P0562P0563

References: static.nhtsa.gov, electronicspecifier.com.