The answer to 'P-trap foul smell' is that a foul odor coming from your sink's p-trap is usually caused by a blockage or buildup in the trap, which allows sewer gases to escape into your home. Common symptoms include a persistent, unpleasant smell coming from the sink drain. The solution is to clean or replace the p-trap to restore proper airflow and prevent sewer gas from entering your home.
If the problem persists or you're uncomfortable working on your plumbing, it's best to call a professional plumber to diagnose and fix the issue. They can use specialized tools and techniques to properly clear the blockage and ensure your plumbing system is functioning correctly.