Ok so my cat had an accident in the den last night. I didn’t really notice it until tonight. Being right near the heat vents of the room, it definitely does a number on the odor. Think dead fish. Is there a way to get this smell out of the carpet? 
Plain Windex or other generic blue glass cleaner has worked for me. That was on tile flooring or linoleum, though, not carpeting. After a regular cleaning of the area I would just douse the whole thing with the window cleaner and let it air dry, and all smells, staining, etc. just went away like nobody’s business. With carpet though, you should probably test a small area first to make sure it wouldn’t damage it, or make it change color, etc.
Small warning: glass cleaners sometimes contain ammonia- be careful not to mix with anything that contains bleach.
I bought stuff at the pet store especially designed to fix this, which worked. According to a customer I spoke to there, basically the pricier the better.
Do not use anything with ammonia in it to clean up urine. I repeat, DO NOT USE ANYTHING WITH AMMONIA TO CLEAN UP URINE. Urea, the nitrogenous waste we mammals excrete, is chemically very similar to ammonia, so ammonia smells enough like pee to trigger the “hey, this is the right spot, let’s pee here” response in most animals. That’s the real problem with cleaning up urine, trying to get rid of enough of the smell to keep the animal from peeing in that spot over and over and over and over or other animals from marking over the spot.
Your best bet is probably going to be an enzyme-based cleaner like KOE (kennel odor eliminator) or Nature’s Miracle. You’ll need to really douse the area, too, enough to saturate your carpet pad. (Trust me, the urine has soaked through to the pad by now, and if you don’t get all of that out, you’ll never be truly rid of the smell.) Until you can get to the store and get something like that, though, you can chuck a generous portion of baking soda over the area, let it sit for a while, then vaccuum. You’ll want to change your vaccuum bag when you’re done, believe me.
There’s a product called Nature’s Miracle. It comes in a white plastic bottle with red letters printed on it. I’ve had 4 St. Bernards, 3 Newfoundlands, 4 cats, 2 Iguanas and one Nile Monitor in my lifetime and this stuff works great for any accidents. The only thing is you have to use more that just a squirt for it to work.
-M
Eliminate the cat 
I’ve had good results using Nature’s Miracle on cat pee stains/smells.
Definitely recommend Nature’s Miracle, especially on carpets.
Landlord here.
Use one of the enzyme products, and don’t be shy. Really soak the area.
If at all possible pull up the carpet, cut out the soiled padding and replace it. Padding is quite cheap and doesn’t require any skill to install.
I used Nature’s Miracle and it did not work at all for me. I used up several of the big bottles plus a gallon jug of it. The odor got a little fainter, but if I made the mistake of leaving something like a shirt on that part of the floor, the shirt would then smell like pee.
I also used “The equalizer” which is an odor eliminator used in hotels and the like. No effect.
With clothes, all I needed to do was launder them, but with carpet there was only one case where I got it to go away: I took the carpet outside and let it sit in the rain for a month. After that, it smelled fine.
My personal advice would be to give up now before you waste a lot of money on cleaning products. Oh, and put something where the cat peed so it doesn’t have the option of ever peeing there again.
Dump a box of bicarbonate of soda on it. Ignore for a while and then vacuum up. Usually works, costs very little.
There’s a mineral called zeolite which will take the smell of anything out of anything. That might be the active ingrediant in Nature’s Miracle.
And in case you’re not aware of it: DO NOT USE BLEACH. Urine contains ammonia; adding bleach would be a disaster.
The few times this has happened in our house, I just doused the area with an OxyClean solution.
It seemed to work fine.
I’m intrigued. There’s enough ammonia in pee to create chlorine gas? Also has anyone heard about using a diluted white vinegar solution?
http://boards.straightdope.com/sdmb/showthread.php?t=197102&highlight=litter+bleach
According to the above post, it can happen. Even if it’s only an extremely small chance it will happen, the resulting gas is so toxic I would not under any circumstances risk it.
Vinegar should work.
“Spot Shot”, available at Home Depot or for about 2/3rds less at Costco works wonderfully for Dog whiz. My cat never, ever peed on the carpet, so I never had that specific problem.
Spot Shot works on a lot of different types carpet stains, including ones I’d have thought to be impossible to get off.
I gave in and bought carpet runners to cover up the area where my cat goes “illegally”. It’s unattractive, but much easier on the nose.
I used to manage the “Cat Room” in a large pet store, and I have probably experienced a couple hundred total cat-years as a cat owner. I have tried everything twice. Here’s my advice:
–Nature’s Miracle works, but it’s needlessly expensive.
–OdorMute is the same enzyme as Nature’s Miracle, but is VASTLY cheaper–by like a factor of a hundred.
–These enzymes work via a chemical process, so if they’re NOT working for you, there’s probably chemical interference. IOW, if you try soap or bleach or something first, residue might interfere with the enzymatic process of the OdorMute. It’s too late and you’ve used another chemical, rinse rinse rinse rinse rinse first, and be prepared to do several applications of the enzyme.
–Despite Cecil’s word on the matter, vinegar does NOT work.
–I’ve had some success recently with OxyClean; a cat peed in a basket of laundry, and two cycles of OxyClean took care of the odor.
Nonetheless, I swore 5 years ago that I would never own another cat. Since then, my only exposure has been to friends’ cats, thus reinforcing my vow.
i will also state that washing the affected area with any type of soap or detergent will make the enzymes not work. the soap protects the fibers, or something, from the enzyme.