How do I reset my 2004 chevy impala computer?

Resetting a computer on Your 2004Chevrolet Impala takes a bit more finesse than doing the same on a desktop, where You can just hit it with something heavy and get it to behave. Just me OK then, we'll do this the gentle way. By far the easiest thing to do is drive to an AutoZone and have one of the clerks there reset it for You, if You don't have Your own Scantool or equivalent. You can pick up a very cheap bluetooth ODB-II dongle from Amazon for under twenty bucks, and pair it with a free app on Your mobile phone to have a more modern scanning setup --- but, the old style single function Scantools are still fine. Either will let You reset the codes and the ECU. If You want to go the low tech manual route, just disconnect Your battery. Remove the negative battery cable and set it aside, then turn the headlight switch to the ON position to drain the ECM of any residual power. Wait at least 10 minutes, and then turn it back off, re-hook up the negative battery cable, and go ahead and properly start Your Impala; the computer should be reset.