I all. It's been awhile since I refreshed my ECU by disconnecting the battery. How long should the negative terminal be disconnected.....15 minutes? 30 minutes? Does it matter? I'm planning on disconnecting it for 30 minutes and then will be resetting my radio stations, and seat positions. The reason I'm refreshing the ECU at this time is because I want to check and see if it has any affect on 1 Pending code and an eventual CEL for the same code P0440 (Evaporative Emmission System) that periodically comes on. . I know it can't hurt and it's probably a good idea to do periodically, to take care of any possible glitches that can occur periodically. I was just wondering if the time it's disconnected really matters. Thank all.

 

When I had a CD jammed in the player, I asked the same question regarding the ECU reset. I was told 5 to 10 minutes will reset everything.