I have a 2003 mustang that doesn't pass smog but has no codes so I take it to get the smog and it gets rejected doesn't fail it gets rejected also they tell me I had took off the battery but I haven't took it off all they tell me is to run the car and I run it and still rejected but no codes

when you reset the computer, it sets a bunch of MIL not readies. when you only have 1 mill not ready left, it will pass. So drive it a while and pray it does that before setting codes again. good luck

I'd also have the battery and charging system tested, in case memory is lost due to weak battery state of charge.

Thank you guys. Still got rejected after I ran it and I'm going to check the charging system. Any chance the computer bad ?