Quote:
Originally Posted by serialk11r
Wait is it actually true that they can tell if an ECU has been reflashed back to stock? Dealers do that for factory recalls all the time, it can't possibly make you fail...
Thankfully, my car ain't registered in California, so I get to keep my mpg gains  |
Yes, manufacturers can tell when a ECM has been reflashed. When a dealer flashes the ECM it doesn't flip the tamper bit because it is an authorized flash that is accounted for in the new flash. The tamper bit isn't looking for the number of times an ECM is flashed - it is looking for deviations from the factory authorized flash.
Say you factory software version 1.00. The ECM will know that for version 1.00 the check sum should be A. You can flash version 1.00 as many times as you want and the checksum will be A so the tamper bit doesn't flip.
When the factory comes up with a new software version it also tells the ECM to look for a new checksum. So version 1.01 may have a check sum of B. Again, you can flash this as many time as you want.
You can also flash version 1.00 back onto the ECM without an issue.
The tamper bit get flipped when someone flashes unauthorized software, and the ECM runs a check sum and gets a result different from the expected result.
You might ask why someone making a new tune doesn't just change the checksum to so that the ECM sees what it expect to see. The answer is that it they do (you need the checksum to work or the car won't start) however the tamper bit part of the ECU that is also looking for checksums is encrypted. So the tuner will need to break that encryption.
Of course any software can be hacked but OEMs don't make it easy. In the past that encryption was model year based so if you could crack one ECM you were good and could create a tune for that specific engine and model year. Now they are VIN based so just because a tuner hacks one car doesn't mean that software will work on another car of that year. The idea is to make it not worth the effort. Of course there is an arms race between the OEMs writing the software and the tuners trying to hack it and OEMs have really stepped up their game now that the market is moving to over-the-air software updates.
Chevy claimed the C8 ECM couldn't be hacked when it was launched. I don't think anyone has been successful to date but I'm sure it is only a matter of time. The 2017 Duramax took 2 years to hack and that was with a rebuilt ECM so their is no danger to Chevy that someone will blow up their engine and then claim a warranty.