[Frost__2001]

I've had one thing under warentee denied from Ford, it was related to the Hella headlights being on my car back when I bought it, more or less the headlights malfunctioned badly, and fried my cars complete wiring harness from the lights to the fuse box under the hood, and it was a costly repair.

when it comes to warentee issues on things you've put into the car poorly or half assed, then they will more then likely deny you your clam, otherwise they seem not to care so much if it's done correctly.