Unplug the dishwasher from the mains before opening the door or reaching inside. If the machine stopped mid-cycle there may be hot water and steam in the tub. Open the door slowly and stand to one side to allow steam to escape before leaning in. Have a towel ready to absorb any water in the tub base.

Remove the upper spray arm by pulling it upward off its mounting post, or by unscrewing it anti-clockwise depending on your model. Remove the lower spray arm the same way. Hold each spray arm under warm running water and use a toothpick, cocktail stick, or wooden skewer to clear every spray hole individually around the full circumference of each arm. Even one or two blocked holes significantly reduces circulation pressure and forces the pump to work harder.

Remove both the cylindrical coarse filter and the flat fine mesh filter by unscrewing the cylindrical filter anti-clockwise. Clean both thoroughly under warm running water using a toothbrush. With the filters removed, shine a torch into the sump cavity and examine the area carefully for any foreign objects — glass fragments, fruit stones, small bones, bottle caps, or pieces of broken crockery that may have passed through the tub during a previous wash cycle and lodged at the circulation pump impeller entrance.

With both filters removed and the sump visible, attempt to rotate the circulation pump impeller very gently using only a non-metallic implement such as a wooden cocktail stick. The impeller should rotate with smooth, even, light resistance through a full turn. Any catching, grinding, or inability to move at all indicates a foreign object jammed around or between the impeller blades. Attempt to identify and carefully extract the obstruction.

With the upper spray arm removed, check the central tower that feeds water to the upper rack spray arm. This is typically a vertical tube running up from the back wall of the tub to the upper rack connection point. Confirm it is fully connected at both ends, not cracked or split, and completely clear — a blocked wash tower prevents water from reaching the upper spray arm entirely while the pump continues to run, which can produce i50.

Refit all spray arms, filters, and any components removed. Plug in and run the hottest available programme — Intensive or 70 degrees. Remain present and listen carefully during the wash phase. You should hear a continuous, strong, steady rushing sound of water being pumped at pressure through the spray system from the very start of the wash phase.