Resolving a Faulty Water Level Sensor on LG WM3700HWA

Understanding the Water Level Sensor
The water level sensor in the LG WM3700HWA monitors how much water is in the drum during a wash cycle. It does this by measuring the pressure of the water that rises to a sensor located near the bottom of the machine’s tub. When the sensor fails, the washer may over‑fill, under‑fill, or stop filling altogether, leading to uneven washing or frequent error codes.

Common Symptoms of a Faulty Sensor

• The machine displays a “E06” error and stops before starting the cycle.
• The washer fills too much or too little water, causing clothes to be too wet or too dry.
• The machine does not fill water at all, even though the water supply valves are open.
• The washer makes a humming noise while it should be draining or spinning.

If you notice any of these signs, it is time to examine the sensor and replace it if necessary.

Tools You’ll Need

• Phillips head screwdriver (size #2)
• Flat‑head screwdriver
• Multimeter (digital preferred)
• Service manual or LG support guide for WM3700HWA (available online)
• Replacement water level sensor (part number 500-4009-000)
• Optional: a small flashlight

Safety Precautions

1. Unplug the washer from the wall outlet before doing any work.
2. Turn off the water supply valves on both hot and cold lines.
3. Wait a few minutes after unplugging to allow any residual pressure in the pipes to release.
4. Keep a towel or a small container handy in case water drips when you disconnect hoses.

Step 1: Prepare Your Washing Machine

1. Move the washer to a flat, level surface if it is not already.
2. Place the washer on a rug or mat to protect the floor from splashes.
3. Inspect the area around the machine for any visible leaks or damage.

Step 2: Access the Water Level Sensor

1. Locate the rear panel of the washer; the sensor is usually behind the back cover near the bottom.
2. Using the Phillips head screwdriver, remove the screws holding the back panel in place.
3. Gently lift the panel to expose the internal components.

Step 3: Inspect the Sensor Wiring

1. Find the sensor’s cable. It is a thin, flexible wire with a connector that attaches to the sensor housing.
2. Look for frayed or disconnected strands.
3. If the connector appears loose, gently pull it back into place and secure it.

If the wiring looks intact, proceed to test the sensor itself.

Step 4: Test the Sensor with a Multimeter

1. Set your multimeter to the resistance (Ω) setting.
2. Identify the two terminals on the sensor. They are typically labeled “+” and “‑”.
3. Touch the multimeter probes to each terminal.
4. A functioning sensor should show a resistance between 500 Ω and 2000 Ω when the washer is not filled with water.
5. If the resistance is infinite or zero, the sensor is faulty and needs replacement.

Step 5: Remove the Faulty Sensor

1. Note the orientation of the sensor before removal to aid in correct installation of the new part.
2. Use the flat‑head screwdriver to gently pry the sensor housing away from the cabinet.
3. Disconnect the sensor cable from the sensor housing.
4. Lift the sensor out of its socket.

Step 6: Install the Replacement Sensor

1. Insert the new sensor into the socket, aligning it with the orientation you noted earlier.
2. Press firmly until the sensor clicks into place.
3. Reconnect the sensor cable to the housing, ensuring a snug fit.

Step 7: Reassemble the Washer

1. Replace the back panel and secure it with the screws removed earlier.
2. Check that all screws are tightened evenly to avoid wobbling.

Step 8: Test the Washer

1. Open the hot and cold water supply valves.
2. Plug the washer back into the outlet.
3. Load a small amount of laundry and start a short wash cycle.
4. Observe the water level and the cycle’s progress.
5. If the washer fills correctly and completes the cycle without error codes, the sensor replacement was successful.

Troubleshooting If the Problem Persists

• Double‑check the wiring connections: A loose connector can mimic a sensor fault.
• Verify water supply pressure: Low pressure can cause improper filling, unrelated to the sensor.
• Inspect the water inlet valves: If they are clogged or stuck, the washer may not fill properly.
• Examine the pressure switch: This component works with the sensor; if it is faulty, you may need to replace it.

Common Error Codes and Their Meanings

Why Replacing the Sensor is Often the Best Fix

The LG WM3700HWA’s water level sensor is a small, inexpensive component that is relatively easy to replace. Replacing it eliminates many of the most common filling issues without the need for more costly repairs or a new washer.

When to Call a Professional

• You are uncomfortable working with electrical components.
• The washer shows additional error codes that you cannot resolve.
• The water supply lines appear damaged or unusually corroded.

In these cases, a qualified appliance technician can safely diagnose and fix the issue.

Preventive Maintenance Tips

• Clean the filter: Some models have a small filter at the back that can clog over time.
• Inspect hoses annually: Replace any cracked or worn hoses to maintain proper water pressure.
• Keep the machine level: A tilted washer can cause uneven water distribution, stressing the sensor.
• Use a water softener: Hard water can mineralize components, shortening their life.

Final Thoughts

Replacing a faulty water level sensor on the LG WM3700HWA is a straightforward procedure that restores proper operation and extends the life of your washer. By following the steps outlined above and exercising caution, you can resolve the issue quickly and without the need for professional help.