P0641: Sensor Reference Voltage A Circuit/Open

What does P0641 mean?

P0641 is a diagnostic trouble code indicating "Sensor Reference Voltage A Circuit/Open". This means there is an electrical break in the electrical/charging wiring — a connector may be unplugged, a wire broken, or a component has failed internally. The ECU detected no signal where it expected one.

Symptoms you may notice

• Check engine light (MIL) illuminated on dashboard
• Intermittent warning lights
• Erratic gauge readings

Common causes

• Damaged or corroded wiring harness
• Loose or disconnected electrical connector
• Failed electrical/charging sensor or actuator
• Blown fuse in the related circuit
• Poor ground connection

What should you do?

Schedule a diagnostic appointment at your earliest convenience. The vehicle is generally safe to drive short distances, but the underlying issue should be addressed to prevent it from worsening.