It sounds like you have a weight sensor on the passenger's seat that can be off but to be sure lets run the codes to see if anything comes up here is a guide to help you.
https://youtu.be/gnSGfEqrf_w
A light is not turning on, but a light is turning on to tell you something? All cars have a red "Air Bag" light on the dash. That must turn on for about six seconds when you turn on the ignition switch. That's for a visual bulb check, and the computer is performing self-tests. If that light turns off after those self-tests, the system is working and all of the air bags will deploy in a crash, under the right conditions. It's when that light turns on while you're driving that a problem has been detected by the computer, it turns the system off so the bags will not deploy in a crash, it sets a diagnostic fault code in the computer, and it turns the light on to tell you.
Totally separate from that is a yellow "Passenger Air Bag Off" information light. The passenger airbag has to be manually turned off, usually with a key, to deactivate it. Only the passenger airbag will not deploy in a crash when that yellow light is on. I've never seen that switch and yellow light in a car.
If the sensor is bad here is how you change (below)
Please let us know if you need anything else to get the problem fixed.
Cheers
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Tuesday, January 2nd, 2018 AT 3:18 PM