when light comes on and says Maint Reqd what needs to be done

It's a reminder to get your 90,000 mile service done- that's a big one- to keep your Jeep running the next 30,000

its telling you its time to replace o2 sensor(by time) There is a clear plastic box up by accel pedal. you can unbolt it and remove small piece of tape from side of it. Reach down in with a tooth pick or needle and slide the little wire to one side and it should lock back into place. Then reinstall. Light should be out.