for them to etest your vehicle it needs to have a certain amount of emissions data in the computer.
If you clear your check engine light, it clears your emission data and your car is not ready for the test
if you don't drive your car often, same thing, it will not have enough data for the test... they will take your money and send you home
not having enough data doesn't mean your car fails, it means your car doesn't pass
after 2 failure to reads you get a conditional pass and you'll be able to get your sticker
no repair is necessary, but they next time it needs an etest, it will need to have the data or it will fail...