P0B18: Hybrid/EV Battery Pack Voltage Sense B Circuit Intermittent/Erratic

P0B18 reports that pack voltage measurement B jumps or drops out briefly instead of failing steadily. The controller detects implausibly fast changes or short signal losses that disappear again, so the fault often shows up as a history code. No manufacturer documents P0B18 publicly; GM, for example, monitors only channel A in its published tables (P0ABB to P0ABD). CARB requires battery voltage sensors of the hybrid storage system to be monitored for circuit faults. Steady faults of channel B use P0B14 to P0B17. Typical triggers are loose sense connectors or chafed leads that react to vibration and temperature, so symptoms come and go.

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 appears and disappears, often stored as history
Battery power limited, reduced electric drive or assist
Vehicle may not reach Ready or may shut down the high-voltage system

Most likely causes

Loose or corroded sense connector
Sense lead chafed, intermittent contact
Battery controller software misinterprets transients

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 P0B18 means

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

Frequently asked questions

Can I keep driving with code P0B18?

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 P0B18?

The most common causes are: loose or corroded sense connector; sense lead chafed, intermittent contact; battery controller software misinterprets transients.

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.