What causes a smelly front loading washer?

Odor in a front-loading washer comes from a buildup of unused detergent, fabric softener, clothing fibers and dirt from laundry. These elements, combined with a warm, moist environment, encourage mold and mildew growth, particularly along the rubber gasket.

Preventing buildup and mold growth reduces the smell in a front-loading washing machine. To fix this problem, sources suggest that the person operating the machine use only a small amount of detergent approved for high-efficiency washers, clean the door and gasket after finishing laundry, increase ventilation in the room or use a dehumidifier to suppress mold growth, and leave the door open slightly to allow the washer to dry. Many front-loading washers also have a clean cycle to eliminate the leftover detergent and grime.