2000 Taurus SE FFV-OBD sensor-engine light on, now off

Hot and humid, car sits outside. Drove to work and parked car in a cold sheltered parking ramp. Lunch hour-left for store, had air conditioning on blast to the store and back from the store, 5minutes each way. Parked in cold ramp again. 5hrs later, when started car, engine light was on. After reading up on this on the internet, I decided to keep driving, but without airconditioner for awhile. Approximately 9 startups later, the light went out. So if this happens to you, it may be a moisture sensor and it will dry out.

I've never heard of any moisture sensor.

If I were you I would go to AutoZone and have my codes pulled for free.