Sure, I realise that. But they have to PROVE the mod caused the failure. Not just say it did.
I am afraid in both the UK and US the VW and AUDI sites have lots of example's where this is not true. I would also reiterate what was said in the original link to the VW site
Chapter 6 - We all know I’m chipped, who cares, they can’t void my warranty without proving my modifications broke the car.
Stop. Seriously, stop it right there. I hate to admit it but I used to be naive enough to think that was the case as well. If it makes you feel better most people (even “mod friendly” dealer techs) have no idea how the always misconstrued Magnuson-Moss Act applies in real life. People like to talk about it like it's some golden ticket to modify cars. People love claiming the dealership has to "PROVE" modifications caused the
problem/failure because they’ve heard it over and over that it's how it all works. It's just simply not true. I’ve had the opportunity to spend some time talking with the guy who goes to court on behalf of Volkswagen in the case of buybacks, “thermal events” (when things catch fire), and warranty denials and I got to grill him on some fact vs fiction warranty stuff. The Magnuson-Moss Act goes all the way back to the 5th paragraph of chapter 1 where I said that last part was important and we'd come back to it… we’re coming back to it.
The purpose of the Magnuson-Moss Act is so legally protect a consumer from a manufacturer trying to void your warranty for using aftermarket parts or services without proving it to be the cause of the failure. The confusion seems to stem from the term "aftermarket.” Aftermarket does not mean aftermarket modifications made to a vehicle, it applies only to direct replacement and maintenance parts made by somebody other than the manufacturer. If the manufacturer tries to say your warranty is void because you got your oil changed at Jiffy Lube instead of at a dealership, the Magnuson-Moss Act would protect you and they would have to prove that the aftermarket oil change caused whatever failed to fail.
If you modify their product to perform outside of it's original specified operating range they have ZERO obligation to "prove" that your modifications caused of the failure. If you push it all the way to court, it's as simple as "it wasn't designed for that” and it’s an open and shut case. It still holds true they can't deny warranty coverage on something unrelated, if you have a chipped ECM and your radio display stops working they still need to cover your radio under warranty. But, when you modify the engine to add power the burden of proof is no longer on them for ANY powertrain failure because it wasn't designed to handle the higher loads and stresses than the factory stock XXXhp provides. Legally making anything operate outside of it’s factory stock specified range that is reason enough that the manufacturer does not have to honor the warranty.
That being said, modifications are not a clear cut, black and white voided warranty. The only way to flat out “void the warranty” is if it has a salvage or totalled title.