Whirlpool WUD120 Dryer Sensor Faulty Troubleshooting

Understanding the Whirlpool WUD120 Dryer Sensor Issue

The Whirlpool WUD120 is a popular, front‑load tumble dryer that relies on a moisture sensor to determine when clothes are dry. The sensor, typically located on the drum interior, measures the moisture level of fabric and signals the control board to stop the cycle. When the sensor fails, the dryer can either stop prematurely or run longer than necessary, leading to damp clothes or excessive energy use.

A faulty sensor manifests in several ways: the dryer may shut down mid‑cycle with a warning light, the cycle may never complete, or the dryer may over‑run and heat the clothes to a point of damage. While many of these symptoms can be caused by other components, the sensor is often the culprit.

Below is a step‑by‑step guide to diagnose, troubleshoot, and replace the sensor on a Whirlpool WUD120 dryer. Follow the instructions carefully, and keep safety as a top priority.

Safety First

1. Unplug the dryer from the wall outlet before opening the back panel or accessing the interior.
2. Wait for the dryer to cool completely if it has been operating recently; the heating elements and drum can remain hot for a while.
3. Use a sturdy ladder or stool to reach the back panel, and never climb inside the dryer when it is plugged in.
4. Wear safety goggles if you plan to work with the lint filter or when testing the sensor with a multimeter, as small parts may fly off.

Identifying Symptoms of a Bad Sensor

• Cycle stops abruptly during the drying phase with no clear error code.
• The dryer runs for an unusually long time, often 10–15 minutes longer than normal.
• Wet or damp clothes after a full cycle.
• Unusual noises from the drum or sensor area.
• Error codes such as E14 or E17 (specific to the control board, often triggered by sensor failure).

If you notice any of these issues, the next step is to verify that the sensor itself is indeed faulty.

Step 1 – Verify the Sensor’s Presence

The moisture sensor in the WUD120 is a thin metal strip mounted on the inside of the drum near the lint filter. It is connected to the dryer’s control board by a small, insulated cable.

1. Locate the sensor: open the back panel of the dryer, then lift the lint filter assembly to expose the drum interior.
2. Inspect the sensor for visible damage: cracks, corrosion, or broken wiring.
3. Look for any signs of lint build‑up on the sensor surface, as this can impede its ability to read moisture accurately.

If the sensor appears intact and clean, proceed to the next step.

Step 2 – Clean the Lint Filter and Drum

Sometimes lint buildup can mask the sensor’s true moisture reading, making it seem like the sensor is faulty.

1. Remove the lint filter from the dryer door.
2. Use a soft brush or a damp cloth to wipe away lint from the filter and from the sensor’s mounting area.
3. Inspect the drum’s interior surface for excess lint; clean it with a cloth.

After cleaning, close the dryer door and start a short test cycle to see if the sensor now functions properly.

Step 3 – Check for Error Codes

The dryer’s digital display may show an error code if the control board detects a sensor problem.

1. Power the dryer back on and let the control board reset itself.
2. Observe the LCD screen for any displayed codes.
3. Refer to the user manual for the meaning of any code that appears.

If a sensor‑related code appears (e.g., E14 or E17), it confirms that the control board believes the sensor is defective.

Step 4 – Inspect the Sensor Wiring

Loose or damaged wiring can cause intermittent sensor signals.

1. With the dryer unplugged, gently pull the sensor cable away from the sensor housing.
2. Check the connector for corrosion or bent pins.
3. Inspect the cable for visible cracks or fraying.

If you find any damage, replace the cable or the entire sensor unit, as the cable may be difficult to repair.

Step 5 – Test the Sensor with a Multimeter

A moisture sensor should exhibit a specific resistance value when dry and a lower resistance when wet.

1. Set a multimeter to measure resistance (Ω).
2. Disconnect the sensor cable from the control board.
3. Place the multimeter leads on the two terminals of the sensor.
4. With the sensor dry (use a clean cloth to dry it), record the resistance reading. A typical reading for a dry sensor is around 10–15 kΩ.
5. With the sensor wet (apply a small amount of water or a damp cloth), record the new resistance. A wet sensor should show a significantly lower value, often below 2 kΩ.

If the sensor’s resistance does not change significantly when wet, it is likely defective and needs replacement.

Step 6 – Replace the Sensor

What You’ll Need

• Replacement sensor compatible with the Whirlpool WUD120
• Phillips head screwdriver
• Clean cloth
• Small pair of pliers (optional)

Replacement Steps

1. Remove the old sensor: unscrew any mounting screws holding the sensor in place. Carefully detach the sensor cable from the control board.
2. Attach the new sensor: connect the cable to the new sensor, ensuring a firm connection, and secure it with the mounting screws.
3. Reinstall the lint filter assembly and ensure the drum rotates freely.

Step 7 – Reset the Dryer

After installing a new sensor, the dryer’s control board must reset to recognize the new component.

1. Unplug the dryer again for at least one minute.
2. Plug the dryer back in and let the control board initialize.
3. Start a full cycle and observe if the sensor now properly detects moisture and ends the cycle at the correct time.

If the cycle completes normally, the sensor replacement was successful.

Step 8 – Check the Door Latch and Timer

A sensor may fail to trigger if the dryer’s door latch is not fully engaged, or if the timer malfunctions.

1. Verify that the door latch clicks and locks when the door is closed.
2. If the latch is faulty, replace it according to the manufacturer’s instructions.
3. Inspect the dryer’s timer (usually a mechanical or electronic relay) for signs of wear or failure.

A proper door latch and functioning timer are essential for the dryer to finish the cycle after the sensor indicates dryness.

Step 9 – Inspect Load Balance

An uneven load can cause the dryer drum to spin unevenly, stressing the sensor and leading to inaccurate readings.

1. Make sure the load is evenly distributed across the drum.
2. Avoid overloading the dryer; the user manual typically specifies a maximum weight.

A balanced load ensures consistent airflow and sensor exposure, improving drying accuracy.

Step 10 – When to Call Professional Service

If you have followed all of the above steps and the dryer still fails to detect moisture or the cycle ends prematurely, the problem may lie deeper within the control board or heating elements.

• Control board issues: The dryer’s logic board may have a fault that cannot be resolved by a sensor replacement.
• Heating element failure: If the dryer does not heat properly, it can cause the sensor to misinterpret the moisture level.

At this point, contact Whirlpool customer support or a licensed appliance repair technician.

Maintenance Tips to Prevent Future Sensor Problems

• Regularly clean the lint filter after each use to reduce lint accumulation.
• Check the sensor annually for visible damage or corrosion.
• Avoid overloading the dryer; heavy loads take longer to dry and can stress the sensor.
• Run a “maintenance cycle” occasionally (a short cycle with no clothes) to keep the sensor and drum clean.

By following these preventive measures, you can keep your Whirlpool WUD120 dryer running efficiently and extend the lifespan of its sensor.

Final Thoughts

A faulty sensor on a Whirlpool WUD120 dryer is a common issue, but it is largely solvable with a systematic approach. By cleaning, testing, and replacing the sensor when necessary, you can restore normal drying performance without the need for costly repairs.

Remember always to unplug the dryer before working on it, and if at any point you feel uncertain, reach out to a qualified service professional. Proper care and maintenance will help keep your dryer running reliably for years to come.