Pee on couch

My two years old often manage to pee in our couch and it smells so bad and I don't know what to do! I've tried pet pee spray, vinegar, salt, cornstarch, laundry softener, Yes, nothing works and it stinks! The couch doesn't have removable fabric so I can't put it in the washer. We usually take it to a car wash a few times a year and clean it, but we just did that a few months ago so I'll have to find something else that works in the meantime! Please help a momma out! I'm not in the U.S. either.