I was completing some testing on our new ME 2.7 and 2.8 programmer (Compressor and older V12tt cars) when I was asked yet again if the dealer could spot modified ECUs. I've been asked this question a lot and it has probably been posted elsewhere on this forum but I thought it worth a minute to post the answer once again.

Manufacturers are required to implement a Software Verification Process which allows someone to determine if any part of the software has been changed. In the very early days, this was a basic checksum and thus the process could be subverted by making changes in unused areas that compensated for the table edits a tuner would normally do. Those days are gone and the algorithms in use today are fairly complicated (7K lines of code in the ME97!).

In practice, the scan tool (MB Star Diagnostics and such) simply asks for a Software Verification Number or SVN. This number needs to match the number in MB's data base for that ECU with the indicated processor firmware and calibration firmware. If it does not match, one or both of the firmware elements have been modified. MB performs a SVN check when they reflash their ECUs as a routine quality control check.

The EPA takes a very dim view of playing with the SVN process and tends to fine the living crap out of tuners that do it. Most stay away from messing with the SVN and thus, yes, the dealer can tell if the ECU firmware has been "tuned" if he has a hankering to know.

I tend to advocate tools that allow the owner to install tuned software when he/she wants then go back to stock whenever necessary.

 

I was told if dealer had Star lap-top connected to OBD port, they could easily check for any aftermarket tuning on (Supercharged/TurboCharged app's) by looking @ stock PSI-Boost settings, if tuned their gonna read higher than stock. Best bet is like you say, flash back to stock before any major Dealership warranty claims.