P0CACHybrid/EV Battery Temperature Sensor M Circuit Intermittent/Erratic
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- 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.
- What you may notice
- Warning lamp that may go out again on its own
- Jumping sensor M value in live data
- Likely causes
- LikelyFretting or loose contact in the sensor M circuit
- PossibleCracked conductor or solder joint on the monitoring board
- RareUnstable ground of the monitoring board
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €100 – €2,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.