P0AC5 code meaning
Hybrid/EV Battery Temperature Sensor B Circuit
Powertrain system Generic code P0Axx codes Check engine light
What P0AC5 means
Battery temperature sensor B is one of several thermistors that measure cell or module temperature inside the high-voltage pack; GM's Volt bulletin calls it sensor 2 of nine. P0AC5 is the general circuit code for it, used for an electrical fault the controller does not classify as low, high or erratic. No manufacturer documents this exact code publicly; GM, for instance, reports P0AC6 to P0AC9 instead. CARB requires hybrid battery temperature inputs to be monitored for circuit faults. With one sensor missing the controller has a gap in its temperature picture and tends to limit charge and discharge power. The sensor usually sits on a module or sensing board inside the pack, so checks need high-voltage safety procedures.
P0AC5 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 P0AC5
- Hybrid system or check engine warning
- Reduced electric power and regeneration
- Charging may be slower on plug-in models
Common causes of P0AC5
- Most likelyPoor contact or damaged wire between sensor B and sensing board
- PossibleTemperature sensor B 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 bWiring harnessBms
What each part of P0AC5 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. |
| C5 | The exact fault in that area. |
What to do next
- Note P0AC5 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 P0AC5
What does P0AC5 mean?
P0AC5 means "Hybrid/EV Battery Temperature Sensor B Circuit". Battery temperature sensor B is one of several thermistors that measure cell or module temperature inside the high-voltage pack; GM's Volt bulletin calls it sensor 2 of nine. It is a generic code, so it means the same on every make.
Is it safe to drive with P0AC5?
Drive gently and only to a workshop. With P0AC5 the car can go into limp mode (reduced power) to protect itself.
Will P0AC5 fail an emissions test?
Yes, it can. P0AC5 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 P0AC5 to fix?
Difficulty: workshop only. A typical repair takes 1 to 5 hours of work. This is a job for a workshop.
Will P0AC5 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.