How long do you need to unhook the battery for to clear an SES light? I have a '97 Lumina that I had the battery unhooked(both cables) for nearly 10 minutes and the light came on immediately upon starting the engine.

 

i've heard 15 minutes, but in my experience you need a scan tool to clear codes. autozone has scanners that should be able to clear the codes. you might want them to check codes tho if you suspect something is wrong.