P0C8B code meaning
Hybrid/EV Battery Temperature Sensor I Circuit High
Powertrain system Generic code P0Cxx codes Check engine light
What P0C8B means
P0C8B covers a sensor I signal stuck above its valid voltage, which the controller interprets as extreme cold. An interrupted circuit lets the pull-up lift the line, so the root cause is usually an open connection or a failed thermistor rather than the weather. On the 2016 Cadillac ELR (16OBDG01) GM fails it below −40 °C, an ADC count above 3992, for 1.4 s within 2 s, two trips. Mitsubishi's 2018 Outlander PHEV declares channel [08] open beyond 3.97 V, colder than −62 °C, held 2 s. For the Volt, bulletin 18-NA-342 lists it as sensor 9 circuit high voltage among codes that can come with a Battery Too Cold message above −25 °C and recommends new module software. The short-circuit counterpart is P0C8A.
P0C8B 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 P0C8B
- Battery-too-cold message although outside temperature is mild
- Electric drive limited or unavailable
- Battery heater running unnecessarily
Common causes of P0C8B
- Most likelyOpen wire or loose connector in the sensor I circuit
- PossibleThermistor I open
- Less likelyBattery module software causing false cold readings (GM Volt, 18-NA-342)
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 iWiring harnessBms
What each part of P0C8B 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. |
| 8B | The exact fault in that area. |
What to do next
- Note P0C8B 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 P0C8B
What does P0C8B mean?
P0C8B means "Hybrid/EV Battery Temperature Sensor I Circuit High". P0C8B covers a sensor I signal stuck above its valid voltage, which the controller interprets as extreme cold. It is a generic code, so it means the same on every make.
Is it safe to drive with P0C8B?
Drive gently and only to a workshop. With P0C8B the car can go into limp mode (reduced power) to protect itself.
Will P0C8B fail an emissions test?
Yes, it can. P0C8B 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 P0C8B to fix?
Difficulty: workshop only. A typical repair takes 0.5 to 5 hours of work. This is a job for a workshop.
Will P0C8B 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.