p0aa6??? Please help

Hey guys this is my first post but I've been reading the forums religiously whenever I have a problem. I do battery reconditioning and swapping. Yesterday I had a customer call me for a battery swap. When I arrived the customer had his mechanic with him and he had a huge snap on scanner attached to the car and had already read the code and turned it off. I asked what the code was and he said "p0aa6 it's a bad battery" and I said okay taking his word even though I was not familiar with that code. So I swapped the battery and everything was running fine. The customer called me this morning saying the check engine lights came back on so I decided to do a little research on the code. I didn't find out much and I'm sure if I had the time I could find the answer but it seems like it's a problem with a voltage leak. One thing I did notice is that when I disconnected the ground from the car on the 12v it was sparking like crazy. The leak is obviously not coming from inside the battery pack itself considering I just changed it and the lights came right back on with the same code. I'm sorry if this has already been discussed but I'm on my way to work then to my customers house after work and don't have any extra time to research. Thank you!

 

Thank you. I am currently using a launch creader pro crp123 but like I said in my post the guys mechanic had erased all the codes before I got there for some odd reason. But if I purchase a mini vci it should give more info than my scanner? Is the 3 digit code like a sub code connected to the original code?

 

Thanks! I'm going to purchase one right now. Is there a certain brand or site that you guys would suggest purchasing from ?