Powertrain, generic · Hybrid propulsion

P0C8C Hybrid/EV Battery Temperature Sensor I Circuit Intermittent/Erratic

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P0C8C reports that sensor I changes faster and more often than any real battery temperature could. GM is the only maker that publishes the test: in 19OBDG02, the 2019 hybrid powertrain control module 2 table, each 10-sample window at 100 ms per sample is scored by the summed absolute change of the reading, a score above 10 counts as a failed window, and 4 failed windows out of 5 set the code, Type B, two trips, with system voltage above 10.2 V and no communication fault to the battery interface module. The 2018 table 18OBDG02 contains the same rule. Unlike P0C8A and P0C8B the value never leaves its valid range. Look for a fretting terminal or a wire broken inside its insulation; several erratic sensors at once point to the sensing board.

Likely causes

Fretting or loose terminal on the sensor I connector
Sensor I wire broken inside its insulation
Sensing board with unstable supply or ground

Symptoms

  • Warning lamp appearing now and then
  • Sensor I value jumping in live data
  • Short phases of reduced power

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–2,500
Time1–5 h

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

Parts involved

hv battery temp sensor iwiring harnessbms

Related codes

P0C88P0C89P0C8AP0C8BP0C85

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