Powertrain, generic · Hybrid propulsion

P0CFA Control Pilot Charging Switch A Circuit Low

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

Charging switch A shifts the control pilot from the connected state at about 9 V to the charge-request state at about 6 V by switching in an extra 1.3 kΩ path. P0CFA indicates that the control or feedback line of this switch reads too low, typically a harness wire touching ground or a driver stage in the charging module that has failed shorted. No manufacturer documents this code publicly; CARB requires hybrids and plug-ins to monitor the charging system, and GM's Chevrolet Volt checks the same switch only indirectly through P0CF9 by measuring the pilot voltage it causes in a self-test. Depending on the design, a grounded control line can hold the switch permanently closed or permanently open. The high-side fault is P0CFB, the open circuit P0CF8. Charging may then start unexpectedly or not at all.

Likely causes

Switch control or feedback wire shorted to ground
Shorted driver stage in the charging control module
Corrosion in the inlet or module connector bridging to ground

Symptoms

  • Charging does not start, or starts as soon as the plug is inserted
  • Charging fault message in the cluster

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–900
Time0.5–3 h

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

Parts involved

control pilot switch awiring harnesson board charger

Related codes

P0CF8P0CF9P0CFBP0CFCP0CFE

References: law.cornell.edu, en.wikipedia.org, gsi.ext.gm.com.