How long must I drive after new battery and gas cap to pass smog test?

dont remove power from the system...should be close to reset..some take much more time and miles...they like a steady 15 mile trip..have the codes rescanned again ..it cant hurt

It depends from just a few miles to 50. Sometimes more. There is a procedure for this on the internet how to drive the car to make it ready for the smog

Also, you coild post the error code. The guys at autozone are just sellers and maybe offer a hint, but are not certified techs. I think he just read the code and offered the usual solution or the easiest. By any chance did you filled the tank before this error occured? Maybe try to reset tne error, but this means you have to drive it some more to make it smoke check ready.

you need to know what the code is , you've already learned not to buy cheap parts , the gas cap may well have solved the one code but a different one may be up now , you don't know , then there's the "smog test " which I understand as the actual testing (sniffing )of the exhaust which is separate from when codes have been purged from the ECM. First get the codes cleared then the exhaust can be checked .The catalytic converter takes care of a majority of pollutants . Let us know what happens .

If that code does not clear up driving a 100 miles or more, you have a small EVAP leak, and a smoke test would need to be performed to find it. I'd quit messing around with the gas cap and get it into a good shop to have the EVAP system checked out. But you probably should drive it a bit more to see if the gas cap was the problem. When codes are set, and you get them repaired and cleared there is a minimum amount of miles you need to drive the vehicle, usually over 100 miles. When the car goes to inspection, their scanner can tell when the last time in miles when the codes were cleared, and tell you to come back if the required miles have not ben driven. So you need to getter fixed.

I just today took my 2002 Subaru in for smog test. No check engine light on but they told me it had to be driven 80-100 miles so the memory (history) reset. They said any driving would do it, city or highway, as long as it was 80-100 miles since battery replacement. So, I’m going with that. What sucks is they make me pay again ( a reduced rate though) and they will check memory/history before test. If not reset, no charge. So always ask if the reset has occurred. Bummer is: I didn’t know that so paid $53?? when I take back it’s a $35 charge. So instead of $52 it is costing $88. I will always ask them to check first for reset now. So, that is today’s info I got. Aug 14, 2019. Woulda been nice if Subaru dealer told me that when he changed battery. Now I know.