Its an old wives tale, but i still do it. Before you go to bed at night, disconnect the battery, and turn the key on, and right to on. This would drain the ECM of any reserve power it might have stored. (i know, old wives tale, lol)
When I had the dreaded code 41, I did the work for 8 hours, then disconnected the battery for about 10 minutes. The Check engine light still came on later, and it was the same code, (worried me actually, thought i did it wrong). It would come on and off, and when it was off, there would still be a stored code. So, i did my trick, and it did the trick, plus leaving it overnight.
2009 Pontiac Vibe AWD 2.4
1993 Buick Park Avenue 3800
1984 Chevrolet Citation 2.5 liter four.