B1640 fault code: what it means

B1640: BYD: driver seat belt pretensioner not connected. Belt won't tighten in a crash.

Body · Safety risk

Usual causes, most likely first

1. pretensioner plug loose (often after seat removal)
2. wiring

B1640 by make

Not sure what B1640 means on your car? Ask Credov.

Before you clear it

Write the code down or photograph the scanner first. A code that comes straight back after clearing points to a fault that is still there. A car whose codes were cleared just before you arrived may be hiding one: the scanner's readiness monitors show "not ready" for a while after codes are cleared.

Researched by Credov from manufacturer and workshop sources. A fault code points to where a fault may be; a workshop confirms it with a diagnosis. Browse all fault codes.