F28
Whirlpool Dishwasher
Severity: MinorWhat Does This Error Mean?
F28 means the moisture or humidity sensor in your Whirlpool dishwasher has reported a fault. Some Whirlpool models use a moisture sensor to detect when dishes are dry during the dry cycle. When this sensor fails or gives a signal outside the expected range, the control board displays F28 and stops the dry cycle. Dishes may come out wet, but the wash function usually still works.
Affected Models
- WDT970SAHZ
- WDTA50SAHZ
- WDT730PAHZ0
- WDF975SAHZ
- Whirlpool dishwashers with sensor-dry technology
Common Causes
- Faulty moisture sensor with a damaged or degraded sensing element
- Moisture sensor coated with detergent residue or hard water scale affecting its sensitivity
- Loose or corroded connector at the moisture sensor
- Damaged wiring to the sensor from heat exposure over the dishwasher's lifetime
- Defective control board unable to properly read the moisture sensor output
How to Fix It
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Perform a power reset first. Turn off the dishwasher, unplug for 5 minutes, then restore power. If the F28 was a transient fault, this reset will clear it.
After the reset, run a full cycle with dishes inside to confirm whether F28 returns.
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Select a heated dry cycle if available and run it with dishes inside. Observe whether the dishwasher completes the dry cycle or stops partway through with F28.
If the dishwasher washes normally but stops during drying with F28, the moisture sensor is confirmed as the fault location.
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Locate the moisture sensor. On most Whirlpool models it is inside the door panel near the vent or at the top inner edge of the tub. Refer to your service manual for the exact location on your model.
The sensor looks like a small rectangular or oval probe with two wires attached.
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Inspect the sensor for detergent buildup or mineral deposits. Clean gently with a damp cloth and mild vinegar solution. Allow to dry completely, then run another cycle.
A clean sensor surface is essential for the optical or conductive sensing to work properly.
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If cleaning does not resolve F28, test the sensor with a multimeter or replace it if testing indicates it is out of spec. Order the part by your dishwasher's full model number.
After installation, run a full cycle with dishes to confirm the F28 is gone and the dry cycle completes normally.
When to Call a Professional
Moisture sensor replacement is a moderate DIY task. The sensor is typically located in the door area or along the top of the dishwasher tub. Parts cost $20 to $45. A technician will charge $100 to $175 for diagnosis and repair.
Frequently Asked Questions
Can I still wash dishes if F28 is showing?
Usually yes. F28 typically affects only the drying phase. The wash and rinse cycles often complete normally. Your dishes will come out clean but wet. You can hand-dry them while you arrange a repair.
What does a moisture sensor do in a dishwasher?
The moisture sensor detects when the humidity inside the dishwasher drops to a level that means dishes are dry. When it senses the right dryness level, it signals the control board to end the dry cycle. This saves energy compared to running the dry cycle for a fixed amount of time regardless of actual dryness.
Will using too much rinse aid affect F28?
Excess rinse aid can coat internal surfaces including sensors. Too little rinse aid can leave water droplets that make the moisture sensor think dishes are still wet. Make sure your rinse aid dispenser is set to the correct level for your water hardness.