My car did not pass the smog test, the tech said the bat had been unhooked or codes reset

The most likely cause of this problem is carbon buildup in the EGR valve.

Just to add to this one if you have a trouble code in the computer or the check engine light is on while the engine is running it will fail smog. You will need to repair the reason the code P0404 is happening promechanic is right the most common reason is carbon build up on the egr opening causing it stick closed or on the egr pintile causing it to stay open.A good thing to check is remove the egr valve take a small screwdriver flip the egr valve over gentle push on the egr pintle thats the torxs looking thing. The pintle should moved down not giving resistance then suddenly snap open like it was stuck and suddenly releases. Then slowly push the pintle down till it bottoms out then give it just a little more push then let it go and see if it sticks or closes. But what I always do before I even doing anything else is take the scanner but yours would have to be able to read live engine data and see what the egr valve reads at rest key on engine off that would be the voltage reading from it. It should read 0.5-1.0 volt but usually around 0.77 volts that can tell you if you have a sticking open egr valve or possibly a terminal circuit or pcm issue.I have also had those saturns reading too high of voltage at rest and it wasnt the egr valve terminals circuit or the pcm it neaded the pcm reflashed with its same pcm calibration file. Also after removing the egr valve start the engine up and let it run for a few seconds the rpms should race and there should be a loud exhaust leak noise then turn it off. That will blow out any loose carbon and also make sure your egr ports arent clogged.

Also after you repair the P0404 and you clear the codes that will reset all your emission monitors and they will have to be reset before you can get it to pass smog.