Powertrain, generic

P0EF8 Battery Charger A Input Voltage Sensor B Circuit Range/Performance

Check engine lightUsually off
EmissionsNot relevant
Drive cycleRequired
Limp modeNo

P0EF8 is set when input voltage sensor B of charger A delivers a value that is electrically valid but wrong for the situation. No manufacturer documents P0EF8 publicly. GM's rationality test for sensor A, P0D3E in its 2019 plug-in hybrid tables, illustrates the idea: while the car moves at 16 km/h or more, when no plug can be connected, the sensor duty ratio must stay between 8 and 12 %; if 60 of 80 samples taken every 25 ms fall outside, the code is stored as Type B. A charger with two input channels can additionally compare them with each other or with the supply voltage reported by the station. Offset drift or a partial fault in the sensing electronics is the likely cause, wiring less so. Charging may stop or continue at reduced power.

Likely causes

Offset drift of the voltage sensing electronics in the charger
Partial internal fault of the charger input stage
Charger software misjudging the plausibility window

Symptoms

  • AC charging interrupted or slower than expected
  • Code may set while driving without any charging attempt
  • Charging fault message

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€0–2,500
Time0.3–4 h

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

Parts involved

battery charger a input voltage sensor bon board charger

Related codes

P0EF7P0EF9P0EFAP0EFBP0D3E

References: gsi.ext.gm.com, law.cornell.edu.