ECU's history check

[levyraccoon]

Hi,

I would like to find out, if there is a way to check the history of an ECU. Or, to see, if the car's ECU has been changed.
Namely to find out- proof-, if the car has been in an accident, or not.
I bought my car from a dealer a few years ago- used certified.
A year ago, after a fender bender the body shop pointed it out to me, that the car has been in a serious accident.
Ran Carfax came back clean. Yet, more and more small signs shows that the car has been in an accident.

Clearly whoever sold the car to me fixed it without reporting it, then sold it to me as a clean car.

Many people- including authorities told me that there is nothing I can do now, three years after the purchase.
Yet, it drives me crazy that unsuspecting, innocent people can end up like me with dealers like mine around.

Mine only hope is- I am not after any capital gain- to somehow proof, find evidence in the ECU for bag deployment?, tampering? missing codes? etc.

Any input appreciated.