Originally Posted by Zsteve

My last three cars have had tunes and have been in the shop for repairs and never had an issue with them reading the ECU if it wasnt ECU related. Ive even had part replaced under warranty that went bad because of the tune, like blown diverter valves and things like that. The shop just replaced them and I was on my way. Now it could depend on the shop but if you come in for a problem, they may read your ECU for codes but they will not read it to see if there has been a tune. Again, Im not certain but I dont think their diag machine can even detect if there has been a tune added. Maybe someone with more knowledge of the diag machines can chime in a clearify this. But Ive yet to have a problem with tunes or bolt on mods when it cam to getting things fixed. Now if the ECU goes bad then yes they will check for that.

And again this is personal experience with my last three cars that have had full bolt ons and tunes.