They can only deny a specific claim if they can show that the damage was caused of the change you made. Period!
The Magnuson-Moss Warranty – Federal Trade Commission Improvement Act of 1975 protects consumers from such fraudulent activity by new car dealers. Under this Act, aftermarket equipment that improves performance does not void a vehicle manufacturer’s original warranty, unless the warranty clearly states the addition of aftermarket equipment automatically voids your vehicle’s warranty or if it can be proven that the aftermarket device is the direct cause of the failure. The easiest way to check this is to look in your owner’s manual under, “what is not covered”. Under Magnusson-Moss Act a dealer must prove, not just vocalize, that aftermarket equipment caused the need for repairs before they can deny warranty coverage. If they cannot prove such a claim or offer an explanation, it is your legal right to demand compliance with the warranty. The Federal Trade Commission (202 326-3128) administers the Magnusson-Moss Act and monitors compliance with warranty law.
Consumer Bill of Rights
from SEMA Action Network
Your Rights to Personalize Your Vehicle
ARTICLE ONE: You have the Right to buy high-quality, reliable aftermarket performance and specialty parts, accessories and styling options.
ARTICLE TWO: You have the Right to use high-quality aftermarket parts and know that your new car warranty claims will be honored. In fact, your vehicle dealer may not reject a warranty claim simply because an aftermarket product is present. A warranty denial under such circumstances may be proper only if an aftermarket part caused the failure being claimed.
ARTICLE THREE: You have the Right to install and use emissions-legal aftermarket performance parts without incurring hassles and onerous procedures during state vehicle emissions inspections.
ARTICLE FOUR: You have the Right to actively oppose any proposed (or existing) laws or regulations that will reduce your freedom to use aftermarket automotive parts and service or will curtail your ability to take part in the automotive hobbies of your choice.
ARTICLE FIVE: You have the Right to patronize independent retail stores and shops for vehicle parts and service. The U.S. aftermarket offers the world's finest selection of performance and specialty parts, accessories and styling options. These aftermarket products satisfy the most discriminating customers seeking personalized vehicles for today's lifestyle.
The foregoing message is brought to you by the Specialty Equipment Market Association (SEMA). If you would like our guidelines on what to do if your new car warranty is denied, check out the Warranty Denied? section of our web site.
New Vehicle Warranties And Your Rights
No aftermarket part or accessory that is properly installed on your vehicle will entirely void your original vehicle manufacturers warranty. According to the provisions in the Magnuson-Moss Warranty - Federal Trade Commission Improvement Act. It is the dealership's responsibility to prove that your modification directly caused or affected the failure you are trying to resolve. With that said, some dealerships are more performance-oriented than others and are more willing to work with customers.
Warranty-related materials, published by the new vehicle manufacturers, state that the installation of aftermarket parts have no effect on the warranty unless such equipment causes the problem that leads to the warranty claim. Nonetheless, some dealers have improperly denied warranty claims even though the claim had nothing to do with aftermarket parts. I.E., just because you install an exhaust system, your suspension failure warranty claim cannot be denied. If you experience a problem with an uncooperative dealership, point out the provisions of the this "FEDERAL ACT". For more information call your vehicle manufacturer or click on the link above to go directly to the Federal Trade Commission's website to find out more about this law.
Is there even more information available to me?
Yes, SEMA, the Specialty Equipment Market Association, has extensive information about this issue. Check out their information at Warranty Denied?
SEMA also keeps track of illegal / unethical practices by dealers regarding this area. If you should have to go to court or to arbitration to settle your warranty complaint, contact SEMA with the details.
What else can I do?
In large cities, there are always other dealers you can do business with. It's a good idea to find out about the most cooperative performance-oriented dealer available to you by checking with clubs, local groups, etc.
If you live in smaller communities, make sure that an uncooperative dealer knows that they are giving you plenty of reason to take you business elsewhere.
If you should have to do that, write the "manufacturer" to tell them that their dealer's activities have caused you to buy from another car company!
Last edited by 4WHLDRFTN; 11-06-2012 at 02:38 PM.