A diagnostic device for a washing appliance, and associated apparatus and method are provided. A control unit is in communication with at least one operational component of the washing appliance and with at least one control switch device. The control unit is responsive to the at least one control switch device to control the at least one operational component. The control unit is further configured to monitor the at least one operational component so as to identify a failure thereof, and to provide an indicia of the failure. A panel member is associated with the control unit, and includes an indicia of the at least one operational component. The at least one operational component indicia is configured to cooperate with the corresponding failure indicia so as to provide a perceptible identification of the at least one operational component experiencing the failure.