How to Easily Test and Replace the Rotor Sensor on an LG Washer

Is your LG front-load washer giving you trouble, like not spinning properly or showing error codes? The rotor positioning sensor (RPS) might be the culprit. This sensor helps the washer detect the motor’s speed and position, and when it fails, the washer may stop mid-cycle or display an error.

Whether you have a gas or electric model, we’ll walk you through how to test and replace the RPS to get your washer running smoothly again.

If you need any replacement parts for your LG washer, you can enter your model number at AppliancePartsPros.com to order them. Most orders arrive in just two business days, and we have thousands of free guides to show you how to install your new parts.

The information in this article may not apply to your specific appliance model. We recommend consulting your manufacturer’s documentation or contact us with any questions.

What you need

• Towel
• Adjustable pliers
• Phillips screwdriver
• Multimeter
• Mallet
• Socket wrench
• 17 mm and a 10 mm socket heads
• Flatblade screwdriver

Safety precautions

When working on any appliance, always keep safety first to avoid personal injury or damage to the appliance or its parts. Here are some tips to keep in mind:

• Always power off and unplug your appliance or switch off the circuit breaker before you attempt any maintenance or replacement work. This keeps you safe by eliminating any risk of electric shock. 
• If the appliance has recently been used, give it plenty of time to cool down before working on it. 
• Take your time while working to prevent accidents and personal injuries. Rushing is the enemy of precision.
• Work in a well-lit area so you can see and access appliance parts.
• Keep your workspace free of clutter and other obstacles. Keep children and pets away from the work area.
• Never work on internal parts with wet hands. Make sure the work area is completely dry.
• Check the user manual to see if there are specific installation or safety instructions related to your appliance or replacement part. 
• Be gentle when handling or removing parts. Excessive force might damage the appliance or cause personal injury.
• Wear insulated work gloves to protect your hands from sharp metal parts and debris.
• When working with wires, avoid touching any exposed wires or terminals. If you need to touch a wire, use a non-conductive tool or wear insulating gloves to prevent electrical shock.
• Always take photos or make a note of wiring terminals or other connections before disconnecting them to make reassembly easier.
• Don’t test live voltage with a multimeter if you’re unfamiliar with how to prevent short-circuiting.
• Consider wearing safety glasses and/or a dust mask when working with chemicals, dust or a large amount of debris to prevent irritation or injury.
• Turn off the water supply at the outlet before beginning repairs. Keep towels ready to catch any residual water in the system when removing parts.

How to test and replace the LG front-load washer’s rotor positioning sensor

Below are the steps to test and replace the Rotor Positioning Sensor (RPS) in an LG front-load washer for proper functionality and address potential issues.

Step 1. Access the rotor positioning sensor (RPS)

1. Unplug the washer from the electrical outlet.
2. Shut off the hot and cold water supply valves.
3. Place a towel under the water inlet hoses to catch any spills.
4. Use pliers to loosen the hose connections and remove them one at a time.

1. Locate the four Phillips screws securing the rear panel.
2. Remove the screws and slide the panel up and out.
3. Find the harness at the back of the washer.
4. Trace the harness to the edge of the rotor.
5. Identify the four-wire plug with White, Blue, Grey, and Red wires.

Step 2. Test the rotor positioning sensor (RPS)

LIVE VOLTAGE WARNING: For this test, the washer needs to be plugged in and powered on. Please be very careful to protect yourself from electric shock, which has the potential to cause serious injuries. Don’t ever test live voltage if you’re uncomfortable using a multimeter.

1. Set the multimeter to DC Volts (V with two lines on top).
2. Insert the multimeter probes into the White and Grey terminals of the RPS connector.
3. Plug the washer back in.
4. Close the washer door.
5. Press the POWER button, but do not press START.
6. Check for a voltage reading of 10 to 15 VDC.
7. If the reading is 0 VDC, test the motor harness.
8. If the motor harness is intact, replace the Main PCB.
9. Move the multimeter probe from White to Blue while keeping the other probe on Grey.
10. Slowly rotate the motor rotor manually.
11. Check for a pulsing voltage reading of around 10+ VDC.
12. Move the probe from Blue to Red and repeat the test.
13. Check for a pulsing voltage reading of around 10+ VDC.
14. If both tests show pulsing 10+ VDC, the RPS is functioning properly.
15. If the voltage remains steady at 10VDC, the RPS is faulty and must be replaced.

Step 3. Test the resistance for confirmation

NOTE: Generally, for every 1 degree in temperature difference, 2 Ohms could be added or subtracted. If the temperature in your home is cooler, resistance would be subtracted. 

1. Unplug the washer.
2. Set the multimeter to KOhms (Ω symbol).
3. Check the resistance between the White and Red wires at the disconnect plug.
4. Check the resistance between the White and Blue wires at the disconnect plug.
5. Readings should be between 8 to 12 KOhms.
6. If the reading is outside this range, the RPS is defective.

Step 4. Remove the rotor positioning sensor (RPS)

1. Use a 17 mm socket wrench and a mallet to loosen the center rotor bolt.
2. Unscrew and remove the bolt completely.
3. Grip the rotor and shake it side to side while pulling it off.
4. Wear gloves to prevent pinching your skin.
5. Use a Phillips screwdriver to remove the four screws securing the harness.
6. Use a 10 mm socket wrench to remove all bolts securing the stator.
7. Hold the stator carefully to prevent it from falling.
8. Flip the stator over and disconnect the four-wire harness plug.
9. Use a flat-blade screwdriver to release the RPS from the stator.

Step 5. Install the new rotor positioning sensor (RPS)

1. Clip the new RPS onto the stator.
2. Reconnect the harness plug.
3. Align the stator holes and insert the bolts.
4. Tighten the bolts manually.
5. Use a 10 mm socket wrench to fully secure the bolts.

Step 6. Reassemble

1. Use a Phillips screwdriver to reattach the four screws securing the harness.
2. Position the metal bracket on top.
3. Align the rotor with the splines and push it in while moving it side to side.
4. Insert the 17 mm central bolt and tighten it with the socket wrench and mallet.
5. Slide the rear access panel back in, top-first, and secure it with four Phillips screws.
6. Attach the inlet hoses by hand for the first few threads, then tighten them with pliers.
7. Turn on the water supply and check for leaks.
8. Plug the washer back in.
9. Turn on the washer and run a test cycle.
10. Observe for proper operation.

Find more DIY resources

Thanks for reading! We hope this guide helped you test and replace the rotor positioning sensor in your LG front-load washer. For any other parts you may need, just go to AppliancePartsPros.com with your model number and we’ll help you take care of the rest! We’ve got over two million parts in stock, and most orders arrive in just two business days.

Need some extra help? Give us a shout at 1 (877) 477-7278 or start a chat with us at your convenience. While you’re waiting on your new parts, check out our DIY blog and watch our video tutorials on YouTube. Follow us on Facebook, X and Instagram to stay connected and explore the latest repair guides!