Across the pond here in the US of A, we have the Magnuson-Moss Warranty Act.
Simply put:
Summary
When accessorizing your vehicle with aftermarket parts, your warranty claim cannot be automatically denied, nor can your warranty be voided, if you install non-OEM parts in your vehicle. The burden is on the dealer to prove the aftermarket parts caused the failure. For example, if your windshield wiper motors fail, your vehicle’s warranty claim can’t be denied because you installed aftermarket windshield wipers that are different from OEM (Original Equipment Manufacturer) parts. Similarly, if a wheel bearing fails or a fan belt snaps and you have an aftermarket exhaust installed, the dealership would have to prove the exhaust system caused the bearing failure or the belt to snap in order to deny a warranty claim. In these types of scenarios, the dealership should have no reason to deny your claims.
This also came about by dealers way back when stating that if you did not have them service your vehicle, they would void your warranty.
If you did an aftermarket exhaust and burnt out an exhaust valve, they would have good reason to deny your claim, but if your timing belt broke after installing the aftermarket exhaust, it could not be considered that the exhaust had any part in the failure of the belt.
With Harleys, it's a big thing here that if you install a trailer hitch on your bike that it voids your warranty. Again if the clutch or trans went south while pulling a trailer, they would have merit to void the repair because of the hitch and pulling a trailer. But they could not void a warranty claim against a bad fuel injector nozzle.
So guys, don't be pushed around. I'm sure that the UK or EU has a similar law covering the same type of warranty voiding policies.
