P0CAA code meaning
Hybrid/EV Battery Temperature Sensor M Circuit Low
Powertrain system Generic code P0Cxx codes Check engine light
What P0CAA means
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.
P0CAA at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor1 to 5 hours
- Clears after repairAfter a drive cycle
Symptoms of P0CAA
- Warning lamp with strongly reduced battery power
- Battery cooling running without reason
Common causes of P0CAA
- Most likelySensor M signal shorted to ground inside the pack
- PossibleThermistor M internally shorted
- Less likelyMeasuring input of the cell monitoring unit defective
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hv battery temp sensor mWiring harnessBms
What each part of P0CAA means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| C | Area: hybrid propulsion. |
| AA | The exact fault in that area. |
What to do next
- Note P0CAA and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0CAA
What does P0CAA mean?
P0CAA means "Hybrid/EV Battery Temperature Sensor M Circuit Low". P0CAA means the voltage at sensor M has dropped below its valid band. It is a generic code, so it means the same on every make.
Is it safe to drive with P0CAA?
Drive gently and only to a workshop. With P0CAA the car can go into limp mode (reduced power) to protect itself.
Will P0CAA fail an emissions test?
Yes, it can. P0CAA is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0CAA to fix?
Difficulty: workshop only. A typical repair takes 1 to 5 hours of work. This is a job for a workshop.
Will P0CAA clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.