P0CB4: Hybrid/EV Battery Temperature Sensor O Circuit Low

P0CB4 reports a signal voltage of sensor O below its lower limit. The sensor is an NTC thermistor biased by a resistor on the measuring board, so a short to ground or a shorted element looks like extreme heat. GM's HPC2 table 18OBDG02 fails the test when the converted value is above 160 °C in 8 of 10 readings at 100 ms, Type B, with more than 10.2 V supply; the 2011 Volt table used 87.5 °C, a raw count below 680, for 1.4 s within a 2 s window over two trips. In GM's 2019 table the pack over-temperature monitor P0A7E is suspended while such short codes are active, because a false hot reading would otherwise trigger it. Mitsubishi calls P0CB4 a short of module sensor [14] on the Outlander PHEV: under 0.12 V, roughly above 125 °C, for 2 s.

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

Live data showing an implausibly hot module
Strongly reduced battery power with warning lamp
Battery cooling running without obvious need

Most likely causes

Signal lead of sensor O shorted to ground in the pack
Thermistor O shorted internally
Input stage of the cell monitoring unit defective

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
With the connector unplugged, check whether the signal wire is making contact with ground.
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 P0CB4 means

P: Powertrain: engine and transmission
0: Generic code: same on every make
C: Subsystem depends on the code range
B4: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0CB4?

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 P0CB4?

The most common causes are: signal lead of sensor O shorted to ground in the pack; thermistor O shorted internally; input stage of the cell monitoring unit defective.

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.