I can only speak for California and Washington State, the inspection includes a sniffer pipe in the exhaust of your vehicle. They put year, make and model along with the vin # in a computer to give base line numbers on what your vehicle co and o2 should be according to that states guidelines. If you don't pass you need to show that you spent up to $500.00 to get it to pass. If you have an inspector who feels that the headlights or tail lights are not conforming, they can make life tough (this rarely happens, but I have heard stories). Goodluck!