It can be a number of faults. Incorrect grip, poor takeaway, slight out to in swing or a slightly open club face at impact. The main thing is, if you can't cure it yourself and you are not happy with playing with a fade then seek professional help through a lesson with a PGA pro.
However what you might want to bear in mind, is that providing it is a regular fade and not an out and out slice, although it will rob you of extra yards a fade will stop much quicker than a draw. Therefore it will land and stop better on a green than a draw which normally flies on a lower trajectory and then runs on landing
dryinator.....(is that the terminator in dry-joys?)......Most of us sliced it a bit (if not a lot!) in the early days of learning. My first pro put me on the right tracks with the correct grip, posture etc. then flattened my backswing......a great deal.....to get the feeling of a flatter swing you could try the old tried and tested baseball swing drill. Learn to turn your body well with a flatter plane and the worst will be over forever.
Without a decent grip though you'll still be in trouble and I'd recommend you see a good pro, even if it's just for a few lessons.....it'll save a lot of heartache (and range balls!!)
It so much depends upon where you are aiming and where it finishes.
If it goes right of aiming point its aslice, goes left of aiming point and lands round about where you were aiming its a fade.
Grip is the most likley cause right hand too far v of thumb pointing towards left sholder maybe.
when I suffered from a major power fade I used to try all sorts of things, what worked for me though was to move my left hand further round the grip, so that you can see more of your knuckles on your gloved hand. Not guarenteeing anything but it worked for me...sometimes too well as I strated hooking the ball.