P0B1B: Hybrid/EV Battery Pack Voltage Sense C Circuit Low

What it means

The control module detects a low signal in the hybrid/EV battery pack voltage sense C circuit.

At a glance

• Usually lights the check-engine light
• The engine or gearbox may go into limp mode

How it works

The battery management module monitors the voltage signal from pack sense channel C. P0B1B sets when that signal is lower than the module expects, which can result from a short to ground, a sensing-circuit fault, or a poor connection.

Common causes

Most likely first.

1. Signal wire shorted to ground
2. Sensing circuit fault
3. Poor electrical connection

Symptoms

• EV/hybrid system warning light on
• Reduced power output or limp mode
• Charging may fail or be slowed
• Reduced electric range

How to diagnose it

1. Save freeze-frame data and check live data for channel C against the other pack-sense readings to confirm the low signal and note when it occurs.
2. Look for related voltage-sense codes that may point to a shared connection or module issue rather than channel C alone.
3. Inspect the channel C wire and connector for chafing, crushed insulation, corrosion, loose terminals, or a connection contacting ground.
4. Using the manufacturer's wiring information, test the channel C circuit for a short to ground and check its connections against the specified values.
5. If the circuit tests correctly, arrange a high-voltage-safe evaluation of the channel C sensing element and battery monitoring hardware.

Common fixes

• Secure a loose channel C connector and clean or repair poor terminal contact.
• Repair insulation damage where the channel C signal wire is shorting to ground.
• Replace a damaged channel C connector or sensing wire.
• Replace a confirmed faulty sensing component or battery monitoring module.

Can I keep driving?

Reduced power or limp mode may make driving unpredictable, so limit use and avoid fast roads or heavy loads. Stop if the vehicle loses substantial power or shows a high-voltage battery warning.