vikings1

I noticed my 98 cobra smoking when my wife drove it, thinking the worse.......i dropped it off and it was only the pcv valve and a bad o2 sensor. Anyone experience this before?? Oh yeah.....the check engine light was on and they told me to take it to a Ford dealer because it came up as a theft code and they would be the only ones to remove it!! Is that bullcrap or truth?? Any input would be welcomed. Thank you in advance.