The law that Nisco and others mention that protects us from dealerships saying that we cannot add aftermarket parts cause doing so would void the warranty is called the Magnuson-Moss Warranty Act and it can be viewed
here.
Now you have to understand regardless of the Magnuson-Moss Warranty Act, the way Hyundai has set up their Warranty Rules and procedures is that if an aftermarket part is installed and replaces a genuine Hyundai part then the genuine Hyundais parts' warranty is void. The aftermarket part replacing it would then have its own warranty. Hyundai has no obligation whatsoever to do any warranty work on the aftermarket part.
This is stated in page 24 of the
Official Hyundai Warranty Coverage guide.
Further more, in section 4.1.14 of the
Warranty Policy and Procedures manual, it states what is not covered which are...
Damage or failure resulting from:
1-Use of parts other than Hyundai Genuine parts
2-Any devices and or accessories not supplied by HMA
3-Modifications, alterations, tampering, or improper repair.
4-Parts or accessories used in applications for which they were not designed or not approved by HMA.
True, Hyundai would have to prove that the aftermarket part is the cause of the failure, and most dealers realize that it is to their best interest to continue having good customer relations with their customer. Therefore alot of them do not mind the aftermarket items being installed. In fact some are doing it themselves realizing the profit potential in selling and installing such items. But there are some that still refrain form doing so and can and will tell the customer the warranty is void thus having the owner to pay for any repair caused by the installed aftermarket part. The odds are in the modifiers favor but still it does happen.
It also depends if the dealership/service department installed the part. Dealer A would not mind installing a supercharger, etc (if they knew how), but Dealer B would not, so you go to a third party. In both cases the the warranty to the engine is null and void. But the supercharger has its own warranty. If anything goes wrong with the engine down the line, dealer A (since they installed it,) would work on the engine and the aftermarket item, dealer b would tell you to go to the 3rd party for the work unless you want to shell out the money to have them do it.
I have done countless modifications on my Santa Fe and all have been minor things, anything major such as a supercharger, dual exhaust I would not even do until my warranty runs out and this is only because my favorite dealership would not work on the warranty part being replaced if the aftermarket item were to be installed.
So bottom line, No, minor modifications as adding altezzas lights, K&N filters, neons, etc would not void your warranty if done right and if the instructions were followed correctly. (Besides if done correctly there should not be any problems down the line.) But major items such as superchargers, dual exhaust will void the warranty unless you get it in advance a written statement from the dealership thats installing the item that it would not void the warranty.
Now I say all of this from the modifiers point of view, and I could be missing something or totally wrong in my analysis of the warranty. Maybe fellow member lowsonoma1999 can give us the dealerships point of view.
TS out.