Powertrain, generic · Hybrid propulsion

P0C9C 14 Volt Power Module Current Sensor B Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P0C9C flags an electrical problem, not further classified, with current sensor B of the 14 volt power module, the DC/DC converter that supplies the 12 V network from the high-voltage battery; GM calls it the accessory power module (APM). In GM's 2013 eAssist table sensor B is the APM output current sensor, while sensor A (P0A86 to P0A8A) measures the input side. No manufacturer documents P0C9C publicly; GM uses only the low and high codes P0C9E and P0C9F plus the A/B correlation code P0CC5. CARB rule (e)(15.3.1) calls for continuous range and continuity monitoring of such inputs. With no trustworthy output current the converter may be derated, and the 12 V battery can slowly discharge. The sensor normally sits inside the module.

Likely causes

Current sensor B inside the power module failed
Poor contact at the power module signal connector
Control software of the power module or hybrid controller

Symptoms

  • Warning lamp, sometimes a charging-system message
  • 12 V battery running low over time

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–1,800
Time1–4 h

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

Parts involved

pm14v current sensor bwiring harnessdcdc converter

Related codes

P0C9DP0C9EP0C9FP0CA0P0A86P0CC5

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