My 2002 Thunderbird did not pass the smog test.

If they did the battery replacement correctly you should not need too. But if they didn’t you need to disconnect one battery terminal, step on the brake pedal for a few seconds, reconnect the battery cable then drive the vehicle for 20 minutes. If you shut the engine off before the 20 minutes have elapsed you will need to start all over again.

Site error

More information would be needed such as out-put of carbon monoxide or hydrocarbons. Do an engine code check; most auto parts stores have a code reader that will loan you to do a check in their parking lot. They will give you a read-out that should specify the problem

You mean tail pipe sniffer ? As opposed to trouble codes ? How many miles ? How much $$$ you got ?

Drive the vehicle for a few days with the gas gauge between one quarter and three quarters. This will allow the readiness monitors to reset. Jim