P0C81 code meaning
Hybrid/EV Battery Temperature Sensor H Circuit
Powertrain system Generic code P0Cxx codes Check engine light
What P0C81 means
P0C81 reports an electrical fault on the input of battery temperature sensor H that the controller does not narrow down further. No manufacturer documents this exact code publicly. In GM's Volt pack sensor H is sensor 8 (bulletin 18-NA-342), and both the 2016 Cadillac ELR table (16OBDG01) and the later Volt tables list only the specific H codes P0C82 to P0C85. Regulators still expect the input to be watched: CARB section (e)(15.3.1) requires continuous monitoring of value range and circuit continuity for such sensors. If the controller cannot trust H it treats the affected cell group as at risk and limits battery power until the fault clears. A generic circuit code calls for a full check of the wiring and connector from the thermistor to the sensing board, inside the HV pack.
P0C81 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 P0C81
- Hybrid or EV warning lamp
- Limited acceleration in electric mode
- Charging slower than usual
Common causes of P0C81
- Most likelyPoor contact at the sensor H connector
- PossibleThermistor H defective
- Less likelyDamaged measuring channel on the sensing board
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 hWiring harnessBms
What each part of P0C81 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. |
| 81 | The exact fault in that area. |
What to do next
- Note P0C81 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 P0C81
What does P0C81 mean?
P0C81 means "Hybrid/EV Battery Temperature Sensor H Circuit". P0C81 reports an electrical fault on the input of battery temperature sensor H that the controller does not narrow down further. It is a generic code, so it means the same on every make.
Is it safe to drive with P0C81?
Drive gently and only to a workshop. With P0C81 the car can go into limp mode (reduced power) to protect itself.
Will P0C81 fail an emissions test?
Yes, it can. P0C81 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 P0C81 to fix?
Difficulty: workshop only. A typical repair takes 1 to 5 hours of work. This is a job for a workshop.
Will P0C81 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.