P0ACAHybrid/EV Battery Temperature Sensor C Circuit
- 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
- 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.
- What you may notice
- Hybrid system or check engine warning
- Reduced electric power and regeneration
- Further battery sensor codes may be stored
- Likely causes
- LikelyPoor contact or damaged wire between sensor C and sensing board
- PossibleTemperature sensor C failed
- RareFault in the battery controller input stage
- 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 – €2,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.