Im sure you can guess from the title what my problem is. So far regular carpet shampoo from a spray can has proved worthless so it's on to some more serious steps. I'm going to get a blacklight bulb from Home Depot to locate the source of the smell and a big bottle of Nature's Miracle cleaner since it gets pretty good online reviews. Any other advice? The only good thing is that I can live with a cleaning product that discolors carpet. The smelly spot is under my bed so I don't care how it looks. I just want to get rid of the damned smell.
My male cat went nuts the last year of his life and sprayed all over my house, so I know what you are dealing with.
For carpet, enzymatic cleaners like natures miracle are not going to do anything. Why? Because the pee will penetrate through the carpet, into the pad and, ultimately, into the floor sheathing beneath your carpet. The enzymatic cleaner can only destroy the urine it touches, and since it won't reach the sheathing you will have the cat pee smell until you do something about it.
For me, the only thing that worked was to pull up the carpet, cut out the saturated pad to expose the sheathing, and then double coat the sheathing with an oil based (vapor barrier forming) paint. Once the paint dries you can add a new swatch of pad and re-stretch the carpet. A good carpet cleaner should take car of the urine in the carpet itself. If it doesn;t you will have to replace the carpet, but its worth a shot to try and save the carpet. You will have to deal with the sheathing either way.
If you think cat pee on carpet is tough, wait till you have to deal with cat pee on porous concrete.