I have 2 cats, started them on the litter tray but they both have there spots in the garden they prefer to use , the litter tray is still always available for them to use but rarely is , the female cat will use it very very occasionally in bad weather , the male cat has been caught having a wee in the bath when it is raining or a new spot in the hallway on the carpet now !
When it is raining he refuses to use the litter tray and if i catch him going toward this hallway spot and literally put him out into the garden (they are locked in overnight) he will reluctantly go and do his wee very quickly and dash back in, I haven't always been here when he is desperate and it's raining though and that's when he has used the hallway carpet !
My male cat is the same!! He looks disgusted at me if it is raining outside and he wants a wee, as if it is all my fault it is raining! (he is also a bit dopey and will, when he sees it is raining at the back door he will then insist on trying to go out the front door and when he realises its raining out the front too he seems doubly aggrieved!! )
If you are happy with him using a litter tray then I would put the litter tray over the place he is using on the carpet for a few days and then move it a few inches each day towards where you want it to be. This has worked for me before. We only have a litter tray in the winter, in the summer they always go out to wee.
Use 2 trays as cats done like sharing normally. I would also pop the litter try in the spot he's been peeing in and make sure you clean up his mess with a proper cat pee cleaner as now he's marked that spot he will use it more.
Thanks all! Will definitely get the other litter tray back out , had only moved to one since they rarely used it (one time in the last 6 months ), but hopefully he might get the idea if I try to place in his pee area.