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.

Likely causes

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

Repair estimate

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

Related codes

References: gsi.ext.gm.com, law.cornell.edu.