It is a common question that car enthusiasts ask themselves when they purchase a brand new sports car off the lot and have the itch to start toying around with it.
The short answer to this question is “very little to virtually nothing” can be modified from original specifications in order to keep your warranty in the clear.
According to the Magnuson-Moss Warranty act, an automaker can’t deny your warranty just because you used an aftermarket part or recycled part as an OEM replacement. If that part was designed to be used in the original matter in which it was installed from the factory, it’s existence can’t be a point for denying your warranty. Although if that part was proven to be the defective point of your repair, then yes, your warranty can be denied.
Going out of the realm of non-oem parts and focusing on the performance side of modifications, virtually anything you do to improve performance or aesthetic looks can and will void your warranty.
- Oftentimes simple add-ons such as air intakes, headers and exhaust systems at first might not look like it can void a factory warranty, but many car companies can use the argument that, “This car was only supposed to handle this amount of power”
- Simple ECU tunes such as ECU re-flashes also can void warranties as now your engine is running under a different performance pattern then it was originally intended for.
- For suspension stuff, springs will almost always accelerate wear or blow out shocks eventually, and that won't be covered. Coil-overs and sway-bars will cause accelerated wear in other parts like bushings, tie-rod ends, and end-links and failures of that stuff will often be denied on the same principle.Your aftermarket stuff over-stressed the stock components causing failure, so no its not covered.
Your best bet is, at least when it comes to warranties is, only modify stuff you can easily reverse before going to the dealer if you have a problem. Fighting them on a warranty denial will usually mean eventually going to court, and with lawyer costs, you will usually end up saving money by just paying to fix the failure in the first place.