maybe you can shed some light on this...my buddies f150 had a MAF go bad...i was driving it to school everyday...had to disconnect the battery on it while i was welding...so i drove it home with 25 miles hwy and the last 10 stop and go...light stayed out...go to parts store didnt make it 50 ft from my house and the light came on...if the MAF is a constant monitor wouldnt the light come on right away or do you think that was when the monitors reset themselves?

 

MAF is not a constant monitor on every system, i just used that as an example. what year is it? and MAF wont show up immediately on a constant monitor system unless it is a code directly related to the MAF, like low input or high input. rich and lean codes will not show up right away even if caused by the MAF

 

its a 2000