The emissions testing facility can't read my obd on my '98 4.6 litre. They said at first that it had been reset because I changed the battery. Since then I have driven it 500 mi. over all conditions and it still wont read it. The truck runs fine, the check engine light works but is not on, and plugging in a code reader shows no error codes. Anyone else have this issue?

 

Should be working fine after 50 miles. Never heard of a obd going bad. Check the fuse. It should be under the hood.

 

Turns out shutting off the ignition in the testing lane resets the obd on some Ford trucks. Ran it thru another drive cycle and to the emission center and had them plug it in without shutting it off, and it passed.