P0BC5: Hybrid/EV Battery Temperature Sensor E Circuit High

What does P0BC5 mean?

P0BC5 reports that battery temperature sensor E delivers a voltage above its valid range. With GM's NTC sensors that reads as extreme cold, pointing to an open wire, a backed-out pin at the sensing board or a cracked thermistor. GM's 2016 table sets it below -69 °C in 8 of 10 samples, the 2011 Volt table and GM's 2019 battery module table below -40 °C for 1.4 s within 2 s, and the eAssist mild hybrid above 4.63 V, about -45 °C, in 7 of 10 samples; all Type B, two trips. On the Chevrolet Volt, bulletin 18-NA-342 links these codes to a Battery Too Cold message at ambient temperatures above -25 °C and prescribes reprogramming. Its counterpart is P0BC4. A pack the controller believes frozen gets strict charge and power limits.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• MIL on after two trips
• Battery too cold, plug in to warm message
• Very limited power or charging

Common causes

• High Open sensor E wire or backed-out pin at the sensing board
• Medium Cracked or open thermistor E
• Low Module software misreading in the cold (GM Volt, reprogramming)

Likelihood is a general estimate across vehicles; your make and model may differ.