Powertrain, generic · Hybrid propulsion

P0CAC Hybrid/EV Battery Temperature Sensor M Circuit Intermittent/Erratic

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P0CAC catches a sensor M signal that jumps around without necessarily leaving its permitted band. GM's HPC2 tables (16OBDG02 to 19OBDG02) add up the absolute changes between successive samples over a ten-sample window at 100 ms; whenever that total passes 10 the window is marked bad, and four bad windows in five lead to a Type B code after two trips. The test runs with more than 10.2 V supply and needs a working link to the battery interface module. Since the value may stay within limits, the hard codes P0CAA and P0CAB can remain silent. Mitsubishi has no jitter code for its pack sensors. Fretting contacts, a cracked conductor on the board or vibration-sensitive wiring are the usual reasons; wiggle tests with live data and freeze-frame records help to localise the fault.

Likely causes

Fretting or loose contact in the sensor M circuit
Cracked conductor or solder joint on the monitoring board
Unstable ground of the monitoring board

Symptoms

  • Warning lamp that may go out again on its own
  • Jumping sensor M value in live data

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 mwiring harnessbms

Related codes

P0CA8P0CA9P0CAAP0CABP0C9BP0CB1

References: gsi.ext.gm.com, gsi.ext.gm.com.