Every mod you have installed in your vehicle including DTC codes are stored and controlled by the ECU and the related to the ECM,thats why we return our cars back to stock before going to the dealer,with my case i have quite a few mods and an extended 7 year warranty,all i need is to run in to a shop forman having a bad day,especially now with all the recalls and piled up the *** with cars coming in for recalls,LOL.