2 stupid questions that are kinda of related, here goes:

1. Does disconnecting the battery clear out codes that are stored in the ECM? When I bought my car 3+ years ago, I never thought about scanning the OBD II port (it's a 1997 SC400) for any stored codes. I've never had a light come up on the dash either. Since my ownership, I've always disconnected the battery and hooked it up to a battery tender when I am not driving it for long periods at a time. When leads me to my second question....
2. Do you guys disconnect the battery when on a battery tender? I've always been taught it helps to prevent any unwanted current/voltage from back feeding into sensitive electronic areas.

TIA!

 

Error codes are persisted even if you unplug the batter. You need to reset error codes with the scan tool.