(Note that if the washing machine has digital controls, rather than a mechanical switch, it almost certainly uses an electronic variable pressure sensor to detect the water level. These three-wire sensors are easy to interface, but we'll leave them for another time).
The glass section of the washing machine becomes at least warm if not hot during a hot water wash. You can feel the glass area with your hand when the procedure is going on to see if it is warm. If the glass section remains cold to your touch it definitely indicates a faulty heating element. Another sign of a faulty heating element is the non stopping wash process. Some times the washer refuses to go to the next cycle and continues the wash cycle till you stop it. This happens when the water does not acquire the pre set temperature.