Run Down Battery and Flex Fuel Question

Got a question that hopefully one of you all will be able to answer and put my mind at ease a little bit.

A little background first: I have a 2015 Crewmax with FFV and it also had the notorious high alcohol reading and rough cold start issue. I had the dealer flash the ecu and it has since been fixed and runs much better. Well I'm worried now that my ecu might have been reset because idiot me left my keys on over night and let my battery die. After I recharged the battery and restarted the truck all the information in my instrument cluster had been reset and that got me worried that it might have reset the ecu and it would have to be reflashed. I really have no way of knowing for sure until the temperature drops again. My mpg has been about the same and my my gut feeling is that it didn't reset it but just wanted to see if anyone could tell me for sure. Thanks for the help.

 

Shouldn't reset any setting that have been uploaded by the dealer as part of any program corrections. Normally that information is saved on the ECU unless changed or deleted

 

^^^. What he said. Think of it like a hard drive. Doesn't matter if it doesn't have power, the info is written to the ECU permanently.. until overwritten the same way.

 

Thanks for your responses and giving me peace of mind. I figured that was the case but just wanted to make sure.