Either you have a faulty air bag or the air bag sensor is faulty. Either way it should be checked by a professional mechanic. I wouldn't gamble on an air bag failure during an emergency.
common problem with 1998 mystique check engine light on
park light circuit.
That's the overdrive off light
get your transmission modulator replaced
There is a battery light above the engine temperature gauge
The fog light switch on the 98 Mystique is on the headlight switch. When you turn on the headlights, pull the switch towards and the fog lights should come on. Here is a link to the owners manual for the 98 Mystique http://www.analogstereo.com/pdf/om/mystique_owners_manual_1998.pdf
A malfunction has been detected
On a 1998 Mercury Mystique : To the left of your tachometer is the seatbelt reminder light and Under your fuel gauge is the airbag readiness light ( if the light stays on or flashes take your vehicle in to have the airbag ( Supplemental Restraint System , SRS ) system checked out / repaired
May also want to check the module ontop of the transmission, it's located next to the battery, I'm not sure if the part's correct name is a neutral safety switch.
I have a 98 mystique, and when the check engine light comes on, I simply disconnect the positive battery terminal for a couple of minutes. When I replace it, the check engine light is cleared. It resets the computer.
not charging the battery properly... check the alternator.
Normally it means the alternator is failing.