How long can a dishwasher cycle take and why might it run longer than expected?

The dishwasher can run up to 3½ hours depending on soil level, water temperature, cycles, and options selected. The dishwasher may run longer while heating water if the supplied water is not hot enough. Additionally, the dishwasher is equipped with an optical sensor that detects water temperature, soil, and detergent amount, and wash cycles are adjusted accordingly.