Jenn-Air Dishwasher Error Code E:28

The E:28 error code on a Jenn-Air dishwasher indicates an Aqua Sensor fault. The Aqua Sensor is an optical turbidity sensor that monitors water clarity during the wash cycle, allowing the control board to adjust cycle length and water usage based on how dirty the water is. When the control cannot successfully calibrate this sensor or cannot detect it at all, it logs the E:28 fault. The dishwasher will typically continue operating in a default mode without sensor input, meaning it will run fixed cycle times rather than adjusting dynamically to load conditions.

There are two primary scenarios that trigger E:28. First, the appliance may not be equipped with an Aqua Sensor at all, which can happen with certain model configurations or after a control board replacement that expects sensor input where none exists. Second, the sensor may be present but calibration fails at startup, usually because the sensor lens is coated with grease, mineral scale, or detergent film that interferes with its optical readings. In either case, the control board determines the sensor is non-functional and sets the fault.

Diagnosis should begin by confirming whether the unit is actually equipped with an Aqua Sensor. If it is, inspect the wiring harness connecting the sensor to the control board for corrosion, loose terminals, or breaks. If wiring checks out, the sensor itself should be inspected for contamination on its optical window and cleaned carefully. A sensor that remains uncalibrated after cleaning may need replacement.