I read this on another forum, I can't remember where, but I copied it and made some inquiries.
The techs I talked to indicated it is accurate.
"First, if you leave the vehicle tuned, like I said above, they can tell by comparing parameters that the vehicle has been tuned. That being said, if the vehicle is flashed back to stock, they cannot tell anything aside from the KAM being erased and a P1000 code present...both of which are indicative to either a dead battery or being flash tuned.
In more detail, when a vehicle is flashed, whether it be with a tune or back to stock, the ECM KAM (keep all memory) is erased and a P1000 code is stored(which means emissions controls have been reset and idle tables figures have not been stored), which basically boils down to a complete drive cycle has not been performed. P1000 is basically an invisible code that is stored in the ECM only and does not throw a check engine light. It can only be found with a scanner or factory software. Now all of those exact flags like I said, also show up when a battery has been disconnected for more than 30 minutes too.
So you have 2 ways around it....
1. Flash the vehicle back to stock and then complete a drive cycle before going to the dealer for service. A drive cycle consists of driving for 50 miles all the while, driving at different speeds including stop and go, highway, etc etc. Normal driving of course, from low speed to highways speeds. That then fills the idle tables and stores emissions information too. Therefore leaving no trace of the vehicle ECM ever being tampered with!
2. If the vehicle is not drivable, you then can flash the vehicle back to stock and then turn on the radio and other power accessories to run the battery down to dead status. That then, (if you recall what I said above as far as the battery being disconnected causing the same things), makes the vehicle KAM become erased, emissions tables reset and P1000 code be stored. The difference is, the battery being dead gives you a viable and 100% believable excuse as to why those things were stored in the computer. Hence, making it look like just a dead battery issue, therefore no one becomes the wiser. You just wait to call the tow truck and then use the excuse that the tow truck took so long, you were listening to music and such while you were waiting.
All of the above is direct first hand experience that I have and not speculation. Hopefully it gives a better understanding of how the ECM operates, as far as flash tuning is concerned, and helps to put to rest, some of the fear of using a flash tuner."
DISCLAIMER
YMMV, And I'm trying to get an answer as to whether this is accurate for 2013+ vehicles since we know there is new encryption.
