What would cause the speedometer to fail an inspection?

A speedometer must accurately reflect the vehicle's current speed as well as record the distance traveled to pass inspection. If it does not indicate distance when the wheel is spun, this indicates a malfunction that affects its primary function. A functioning speedometer is critical for gauging speed, which is essential for safe driving, compliance with speed limits, and the overall operation of the vehicle. Therefore, failure to record distance signifies that the speedometer is not working correctly and directly impacts the vehicle's ability to provide necessary information to the driver, justifying a failed inspection.