Scanned my wife's impala to retrieve a code, and purge valve indicates bad.
But I noticed that the TPS at idle is sitting at 19.2. That didn't seem right to me. But no code regarding the tps.
Thoughts?
In addition to the P0496 Evaporative Emmission System High Purge Flow, it also has a B3205 window motor pending, and a C0800 Device Power circuit Malfunction pending/history.
I changed the battery this last weekend also.

I am not a GM tech

However, I do believe after disconnecting the battery on most drive by wires you need to do a throttle body relearn. That could be your 19percent tps at idle. I also don't know alot about the C0800 but that is a power related code so it may be possible that that was caused by disconnecting the battery as well if the module was not asleep at the time. Again don't quote me on that but since nobody has chimed in I thought I would try to help.

Clear all the faults. Drive it. Rescan. What scanner you using?

You might want to research a "drive cycle" for your particular vehicle. To assure you have given a cleared system every chance to analyze itself correctly.

Using HP Tuners.
I replaced the evap purge valve and cleared the codes, and they have not come back. I posted the tmps somewhere else and someone perked up and said the 2016 Impala doesn't have a IACV, and thus relies on some throttle position at idle, and that 19% was not unusual at cold start idle. Car is running well so I guess it's ok.