P0ACA code meaning
Hybrid/EV Battery Temperature Sensor C Circuit
Powertrain system Generic code P0Axx codes Check engine light
What P0ACA means
Battery temperature sensor C is a further thermistor inside the high-voltage pack, corresponding to sensor 3 in GM's Volt bulletin. P0ACA covers a general electrical fault in its circuit that the controller does not narrow down to low, high or erratic. No manufacturer documents this exact code publicly; GM reports the more specific siblings P0ACB to P0ACE instead. CARB requires temperature sensors of hybrid batteries to be monitored like other input components. Losing one temperature input makes the controller more cautious: expect reduced charge and assist power and a hybrid warning. Since sensors C and B often share the same sensing board, check whether neighbouring sensor codes are stored as well.
P0ACA 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 P0ACA
- Hybrid system or check engine warning
- Reduced electric power and regeneration
- Further battery sensor codes may be stored
Common causes of P0ACA
- Most likelyPoor contact or damaged wire between sensor C and sensing board
- PossibleTemperature sensor C failed
- Less likelyFault in the battery controller input stage
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 cWiring harnessBms
What each part of P0ACA means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| A | Area: hybrid propulsion. |
| CA | The exact fault in that area. |
What to do next
- Note P0ACA 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 P0ACA
What does P0ACA mean?
P0ACA means "Hybrid/EV Battery Temperature Sensor C Circuit". Battery temperature sensor C is a further thermistor inside the high-voltage pack, corresponding to sensor 3 in GM's Volt bulletin. It is a generic code, so it means the same on every make.
Is it safe to drive with P0ACA?
Drive gently and only to a workshop. With P0ACA the car can go into limp mode (reduced power) to protect itself.
Will P0ACA fail an emissions test?
Yes, it can. P0ACA 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 P0ACA to fix?
Difficulty: workshop only. A typical repair takes 1 to 5 hours of work. This is a job for a workshop.
Will P0ACA 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.