I’m not exactly sure why our 4 year old cat pissed on the carpet . He has been fully trained since we got him 3 months ago.
I suspect it has something to do with the kids and squeezing him or something, but I won’t dwell on that too long as I now have cat pee on the carpet.
I’ve blotted the mess up and have sprayed some Simple Solutions on it.
I’ll steam clean in a little while and respray the stuff.
But, how do I make sure this doesn’t happen again?
PEe on the cat, and see how he likes it. That’ll teach him. 
It may just be a one time thing. But do what you can to get the smell out completely so the little fucker doesn’t think your carpet is one big kitty box just for him.
If he does it a second time, take him to the vet before he ruins everything. He may have a minor ailment that can be easily treated.
Make sure he can get to the litter box- that nobody closed a door and blocked him from it, or anything like that.
Make sure the litter box is kept clean. Some cats won’t use a litter box if it’s too dirty.
If he’s acting abnormal in any way, take him to the vet just to be sure. We’ve only had one incident of peeing on the floor with our two cats, and it was because the cat who did it had a kitty cold. No, I have no idea why a kitty cold could make her want to pee on the floor, but it’s never happened again since then.
Go to a pet store and buy the expensive nutalizer and figure it’s cheaper than new carpet.
If the cat has never done this before, definitely take him to the vet to be sure he doesn’t have a bladder infection. In a male cat, urinary problems can turn serious very quickly. The most common reason a cat pees outside the box is because he is in pain and associates the box with the pain.
Do NOT steam clean the carpet until you have made absoultely sure that every trace of smell is gone first. If you steam clean, you will just reactivate the odor.You’ve got to treat it with the enzyme stuff, let it completely dry, and then possibly retreat it before steam cleaning.
My cat did this a few weeks ago for no apparent reason. Before our last option, taking her to the vet to see what’s wrong, we tried a different litter brand. She had been using the other one for months with no problem, but she must have decided she didn’t like the pine smell any longer (and it DID stink bad after #2-ing). So we slowly started adding the Arm & Hammer kind and increased the percentages each time we’d clean it out. Now she’s fully on the baking soda kind, we have no more “kitty-poop” stink, and she hasn’t had an accident since.
Also, go to the grocery store and buy Spot Shot. Amazing stuff!