P0BC4: Hybrid/EV Battery Temperature Sensor E Circuit Low

Sensor E is an NTC thermistor with a pull-up resistor, so its voltage falls as it gets hotter; a short to ground therefore looks like an extremely hot cell group. GM's 2016 table sets P0BC4 when the converted value exceeds 160 °C in 8 of 10 samples; the 2011 Volt table and GM's 2019 battery module table use above 87.5 °C for 1.4 s within 2 s; the eAssist mild hybrid flags a sense voltage under 0.3 V, about 90 °C, in 7 of 10 samples. All are Type B, two trips. Volt bulletin 18-NA-342 names it sensor 5 circuit low voltage. Its counterpart is P0BC5 (open circuit, reads very cold); a genuinely overheated pack is reported as P0A7E. Because the controller must assume heat, it cuts charge and discharge power and may run cooling at full speed.

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

MIL on after two trips
Implausibly high temperature for sensor E on the scan tool
Reduced power and battery fan or cooling at full speed

Most likely causes

Sensor E signal wire shorted to ground inside the pack
Internally shorted thermistor E
Moisture or contamination on the sensing board

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 P0BC4 means

P: Powertrain: engine and transmission
0: Generic code: same on every make
B: Subsystem depends on the code range
C4: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0BC4?

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 P0BC4?

The most common causes are: sensor E signal wire shorted to ground inside the pack; internally shorted thermistor E; moisture or contamination on the sensing board.

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.