P0C84: Hybrid/EV Battery Temperature Sensor H Circuit High

P0C84 is set when the sensor H line sits too high in voltage, which the controller converts into an impossible cold reading. The pull-up drives an interrupted circuit upward, so an open wire, a pushed-out pin or a broken thermistor are the classic triggers. In GM's 2012 Volt table (12OBDG01A) the limit is below −40 °C, an ADC count above 4000, held for 1.4 s within a 2 s window; the 2019 table 19OBDG02 uses −69 °C in 8 of 10 samples, Type B. Mitsubishi's Outlander PHEV of 2022 sees an open of sensor [07] above 3.97 V, below −62 °C, for 2 s. A cold-weather complaint with a Battery Too Cold message on the Volt may be software, per bulletin 18-NA-342. The short-to-ground counterpart is P0C83.

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 in mild weather
Electric drive limited or unavailable

Most likely causes

Broken wire or backed-out pin in the sensor H circuit
Thermistor H open
False set by battery module software (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 P0C84 means

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

Frequently asked questions

Can I keep driving with code P0C84?

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 P0C84?

The most common causes are: broken wire or backed-out pin in the sensor H circuit; thermistor H open; false set by battery module software (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.