P0C8B: 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. 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.

High severity. Can I keep driving?If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

Symptoms

Battery-too-cold message although outside temperature is mild
Electric drive limited or unavailable
Battery heater running unnecessarily

Most likely causes

Open wire or loose connector in the sensor I circuit
Thermistor I open
Battery module software causing false cold readings (GM Volt, 18-NA-342)

What to check, in order

Start with the simplest. You can tick off each step.

Read the codes with a hybrid-compatible scanner and write down the freeze frame data
Check the sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
Make sure the battery cooling air intake is clean
Check the 12 V auxiliary battery, which can also trigger warnings
Leave any high-voltage measurements to a specialized repair shop

Good to know

It can trigger limp mode.
It affects emissions.

What each character of P0C8B means

P: Powertrain: engine and transmission
0: Generic code: same on every make
C: Subsystem depends on the code range
8B: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0C8B?

If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

What causes code P0C8B?

The most common causes are: open wire or loose connector in the sensor I circuit; thermistor I open; battery module software causing false cold readings (GM Volt, 18-NA-342).

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.