Why would speedometer and odometer not work on Mazda 626 2000 model?

The speedometer and odometer on a 2000 Mazda 626 may not work due to a faulty vehicle speed sensor (VSS), which sends speed data to the instrument cluster. Additionally, issues with the wiring harness, blown fuses, or a malfunctioning instrument cluster itself could also cause these instruments to fail. It's advisable to check these components to diagnose the exact cause of the problem.