The answer to 'why is my P-trap making gurgling noise' is that a gurgling sound from the P-trap typically indicates a problem with the plumbing system. The P-trap is a curved section of pipe under the sink or drain that holds water to prevent sewer gases from entering the home. When the P-trap is making a gurgling sound, it usually means there is a blockage or issue with the venting system that is allowing air to be drawn back through the drain.
Some common causes of a gurgling P-trap include a clogged drain, a blocked vent pipe, or low water levels in the trap. This can allow air to be sucked back through the drain, creating the gurgling noise. Resolving the issue may require clearing a clog, adjusting the vent pipe, or refilling the P-trap with water.