Anyone seeing this? The passenger seat belt alarm will occasionally go off and continue until the seat belt is engaged. It happens every few days. No passenger or any weight in the passenger seat. When it occurs it's right after beginning to drive. Seems like correct behavior, except there's not actually anyone in the passenger seat.

 

There's a sensor in the seat that detects whether someone is sitting in it or not. Sounds like it's gone bad. Pretty rare, I would guess!

 

There have been several reports of this on the NC model of the MX5 and the problem was that the harness connecting to the sensor was loose. Try finding it under the seat and disconnecting the harness, then reconnecting it to see if that helps.