P0CAAHybrid/EV Battery Temperature Sensor M Circuit Low
- 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
- P0CAA means the voltage at sensor M has dropped below its valid band. Sensor M is an NTC element supplied via a bias resistor on the board, so a grounded lead or a shorted element drags the voltage down and reads as an extremely hot spot. GM's 2018 HPC2 table 18OBDG02 fails the test once the converted temperature exceeds 160 °C in 8 of 10 readings taken every 100 ms, Type B, with more than 10.2 V supply. The 2011 Volt table set it above 87.5 °C, a raw count below 680, held for 1.4 s within 2 s over two trips. Mitsubishi's Outlander PHEV calls it a short of sensor [12]: below 0.12 V, roughly above 125 °C, for 2 s; the remedy there is a new battery module or cell monitoring unit. A real overheating shows as P0A7E instead.
- What you may notice
- Warning lamp with strongly reduced battery power
- Battery cooling running without reason
- Likely causes
- LikelySensor M signal shorted to ground inside the pack
- PossibleThermistor M internally shorted
- RareMeasuring input of the cell monitoring unit defective
- 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: €150 – €3,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.