Just bought a 2004 Elantra with 48k miles and after getting home I noticed the message center in the middle of the dash stating the air bag is off. Does this mean it needs service or is there a way to turn it "On"?? (Owner's manual is missing...)

if you just bought it I would return it to get this fixed, I really don't know what it means when it's on though, sorry.

I believe the newer Elantras have a passenger sensor, so it turns the passenger airbag off if no one is in that seat. Try sitting in the passenger seat and see if the light goes off.

I believe the newer Elantras have a passenger sensor, so it turns the passenger airbag off if no one is in that seat. Try sitting in the passenger seat and see if the light goes off.

ding ding ding, we have a winner

There is a sensor in the seat that will turn the air bag on if the passenger is 45 pound or over

The last answers are correct. This vehicle uses an "Occupant Classification System" and will adjust the deployment configutration depending on the size and position of the occupants. For more information visit these web pages
http://www.airbagsolutions.com
http://blog.airbagsolutions.com/archive/2007/11/18/why-is-my-airbag-light-on.what-should-i-do.aspx
http://www.airbagsolutions.com/docs/ocs.pdf
http://www.airbagsolutions.com/resources.aspx
http://blog.airbagsolutions.com/