P0B71: Hybrid/EV Battery Voltage Sense K Circuit Intermittent/Erratic

P0B71 belongs to the unsteady fault type: the channel K reading flickers or drops out momentarily without staying beyond a fixed limit. No manufacturer documents this code publicly. Neither GM's hybrid tables from 2011 to 2019 nor the Ford and Chrysler bulletins on cell sense codes mention it, although they cover the open, plausibility, low and high codes of neighbouring channels. Its basis is the CARB requirement to monitor battery voltage sensors of the energy storage system as input components. In a workshop the approach would be a wiggle test on the module harness while watching cell voltage K live, plus a check of the connector terminals for fretting corrosion.

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

Warning that comes and goes
Occasional short loss of electric power

Most likely causes

Fretting corrosion on channel K connector terminals
Sense harness under strain losing contact with movement

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
Gently move the wiring with the engine running and watch whether the reading changes.
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 P0B71 means

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

Frequently asked questions

Can I keep driving with code P0B71?

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 P0B71?

The most common causes are: fretting corrosion on channel K connector terminals; sense harness under strain losing contact with movement.

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.