P0CA9 code meaning
Hybrid/EV Battery Temperature Sensor M Circuit Range/Performance
Powertrain system Generic code P0Cxx codes Check engine light
What P0CA9 means
P0CA9 reports that sensor M stays within its electrical limits yet disagrees with what the remaining pack sensors measure. GM's 2012 Volt table 12OBDG01A only runs the comparison once drive system, plug-in charging and battery conditioning have rested for over 21,600 s; a spread above 25.3 °C from the mean in 50 of 67 samples is a Type B failure. The 2018 HPC2 table 18OBDG02 uses 25.00 °C at 25 ms sampling and is suspended whenever circuit faults of the sensors or a communication loss with the battery interface module exist. Mitsubishi uses P0CA9 for module sensor [12] of the Outlander PHEV: after more than 3,600 s soak and at pack temperatures from −30 to 60 °C, a deviation of 13 °C or more from the mean of all 50 sensors for 0.32 s sets it. Drift or a loose sensor is typical.
P0CA9 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor0.5 to 5 hours
- Clears after repairAfter a drive cycle
Symptoms of P0CA9
- Warning lamp appearing after a long parking period
- Battery power limited
Common causes of P0CA9
- Most likelyThermistor M drifting while staying in its electrical range
- PossibleSensor M lost thermal contact with its module
- Less likelyModule section genuinely warmer or colder, e.g. cooling fault or weak cell
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 P0CA9 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. |
| A9 | The exact fault in that area. |
What to do next
- Note P0CA9 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 P0CA9
What does P0CA9 mean?
P0CA9 means "Hybrid/EV Battery Temperature Sensor M Circuit Range/Performance". P0CA9 reports that sensor M stays within its electrical limits yet disagrees with what the remaining pack sensors measure. It is a generic code, so it means the same on every make.
Is it safe to drive with P0CA9?
Drive gently and only to a workshop. With P0CA9 the car can go into limp mode (reduced power) to protect itself.
Will P0CA9 fail an emissions test?
Yes, it can. P0CA9 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 P0CA9 to fix?
Difficulty: workshop only. A typical repair takes 0.5 to 5 hours of work. This is a job for a workshop.
Will P0CA9 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.