Powertrain, generic

P0EFA Battery Charger A Input Voltage Sensor B Circuit High

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

With P0EFA, the signal from the second input voltage sensor of charger A, sensor B, lies above the plausible window. No manufacturer documents P0EFA publicly. GM's comparable check for sensor A, P0D40 in its 2019 plug-in hybrid tables, trips at a duty cycle of 92 % or more but below 100 %, or at exactly 0 %, in 30 of 40 samples, and is rated Type B. Electrically this points to a short to a supply voltage, an open signal line pulled up by the input stage, or a defective sensing stage inside the charger. Since the measuring channel normally sits on the charger board, the charger itself becomes the prime suspect once plugs and pins have been checked. AC charging is refused or ends soon after it started; the low-side sibling is P0EF9.

Likely causes

Defective measuring stage on the charger board
Open signal line pulled high by the input circuit
Signal shorted to a supply voltage

Symptoms

  • AC charging refused or ends after a few seconds
  • Charging fault message
  • Indicated charging power implausible

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€80–2,500
Time0.5–4 h

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

Parts involved

battery charger a input voltage sensor bwiring harnesson board charger

Related codes

P0EF9P0EF7P0EF8P0EFBP0D40

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