Capitalism is rooted in making a buck. Philosophically, the less one pays, the more one keeps. Trying to get a company to part with its money can be frustrating, even if you've parted with yours based on their warranty.
The aftermarket part must be part of the reason for the otherwise-warranted failure. Claims processors know that a certain percentage of consumers will never pursue a denied claim. This numbers game often leads to erroneous "mistakes" for valid claims. The onus then falls to the consumer to fight for what might rightly be theirs in the first place.
Aftermarket parts are one reason for carmakers to deny a warranty claim. Any non-factory components that's anywhere near a failed original-equipment part can be fingered as a reason for claim denial. If this happens to you, begin by reviewing the written warranty and asking for clarifications of any legalese you don't understand. Federal law protects consumers against unjust warranty denials. The mere presence of an aftermarket part isn't a lawful reason for denialthe aftermarket part must be part of the reason for the otherwise-warranted failure.
A knowledgeable third party can help refute a dealer's assertion that the aftermarket part played a part in the original part's failure. Contact the manufacturer of the aftermarket part to see if they're aware of similar situations and, if so, what happened in those cases. The company might point out fine print on their products' literature that addresses OE warranties. The aftermarket manufacturer might also be able to supply a technical assessment of the problem to support your case.
Researching the problem can reveal if it's prevalent in the vehicle. Dealerships aren't always forthcoming about pattern-failure malfunctions. Manufacturers publish Technical Service Bulletins (TSBs) for dealerships, detailing remedies for recurring problems. For significant defects, the government will mandate a recall, which requires the carmaker to notify customers of the defect and explain the procedure for getting the problem fixed. Recall and TSB information is listed at the web sites below. Also, the EPA gets involved in emissions-systems matters while the NHTSA addresses safety issues.
Basically, the more documentation you can compile to support your argument, the better chance you have of ultimately prevailing. Helpful items include photos of the damaged parts, vehicle-maintenance and repair records, pattern-failure info mentioned above and a written opinion on the possible causes of the problem from a qualified expert. Of course, you should also save all correspondence with the dealer, especially their written explanation of why the original claim was denied.
Often, a persuasive dossier of documents supporting your stance will convince the dealer's service manager to either take care of the problem or suggest a compromise. Failing satisfaction at the level, approach the owner of the dealership. The owner might present your evidence to the manufacturer and persuade the carmaker to reimburse the dealer for the repairs as warranty coverage. You might actually be doing both a favor in the long run.
The next step toward satisfaction is to contact the manufacturer's zone representative. The vehicle's owner's manual should have a customer-service number that can refer you to this person. Present all of your evidence to the zone rep, who's probably aware of certain dealerships' histories concerning customers' complaints. If this still doesn't produce satisfactory results, contact the manufacturer directly. (See contact information in the "Resolving Warranty Disputes" article.) If the manufacturer won't take care of the problem, be sure to save all correspondence, especially the refusal letter that explains their assessment of how the aftermarket part caused the problem.
Mediation, Arbitration, Litigation
A final resort is to involve other agencies in the matter. These include the Better Business Bureau and your state's Attorney General's and Consumer Protection offices. A mediator from The Better Business Bureau or Automotive Consumer Action Program (AUTOCAP) might be able to arbitrate the dispute and suggest an impartial solution based on the evidence. This is less costly and more efficient than filing a lawsuit.
Speaking of which, litigation is your final resort when all other avenues have failed. Claims of about $5,000 or less (depending on state law) can be tried relatively quickly and inexpensively in small-claims court. Larger claims will typically involve attorneys and months (if not years) to try in the state's superior court system.
Fortunately, most repair disputes never progress through the entire food chain. After all, automakers crave repeat customers, and most dealers would rather compromise and have you return for service than drive away their business.