This federal law regulates warranties for the protection of consumers. The essence of this law concerning aftermarket auto parts is that a vehicle manufacturer may not condition a written or implied warranty on the consumers using parts or services which are identified by brand, trade, or corporate name (such as the vehicle makers brand) unless the parts or service are provided free of charge. The law means that the use of an aftermarket part alone is not cause for denying the warranty. However, the law's protection does not extend to aftermarket parts in situations where such parts actually caused the damage being claimed under the warranty.
Further, consumers are advised to be aware of any specific terms or conditions stated in the warranty which may result in its being voided. The law states in relevant part:
“No warrantor of a consumer product may condition his written or implied warranty of such product on the consumers using, in connection with such product, any article or service (other than article or service provided without charge under the terms of the warranty) which is identified by brand, trade or corporate name....” (15 U.S.C. 2302©).
Whats this mean? The use of an aftermarket part will not void your warranty. The only time your warranty will be voided is if
1) The manufacturer is providing a replacement part free of cost.
2) The manufacturer or dealer can prove that the aftermarket part or mod caused the failure or damage.
So what happens if you do an airbox mod and your dealer says your voided the warranty?
Visit the above link for more information.
There are laws in the world to protect the consumer. Its always a good idea to know and understand them. Always fully read both your warranty manual, and your owners manual of your vehicle.
Otherwise you could be screwed over by your dealer, warranty or not.
For example: Did you know Mazda requires all dealers provide either a rental or loaner car if your vehicle is in for service? Its not a dealer "bonus," its a manufacturer requirement.