Litter-Robot 3: Red Light Flashing (Cat Sensor Fault) (2025)


The Litter-Robot 3 is equipped with a cat sensor that detects when a cat enters and exits the globe.

Litter-Robot 3: Red Light Flashing (Cat Sensor Fault) (1)

If the cat sensor has been continuously activated for 30 minutes or more, either by a cat that won’t leave the globe or by too much weight in the unit, the timing light will flash red.

Litter-Robot 3: Red Light Flashing (Cat Sensor Fault) (2)

You will also receive a notification on your phone if you use the Whisker app.

To ensure the accuracy and reliability of the cat sensor, press the Resetbutton after making any changes that will affect the weight of the unit, including emptying the waste drawer, adding or removing litter from the globe, or cleaning or moving the unit. This will recalibrate the weight sensor and circuit board to reflect the changed weight.

Preparation

If the cat sensor detects a cat trying to enter the Litter-Robot during a cycle, the globe will stop rotating and the yellow Cycle light will flash slowly. Once the cat exits, the unit should continue cycling after a brief pause.

If the cat does not exit the robot, or if the cat sensor continues to detect weight for up to 30 minutes, the robot will display a flashing red light indicating a cat sensor fault.

If the cat has exited but the robot continues to display a slow flashing red light, press the Resetbutton to continue the cycle.

Success: If your unit returned home and displays a solid blue light, you've been successful.

Unsuccessful: If your unit is not displaying a solid blue light after returning to home position, or cannot complete the cycle, please continue with troubleshooting.

Troubleshooting

Check for obstructions

Check for obstructions that might prevent the cat sensor from functioning.

  1. Make sure Litter-Robot is on a firm, level surface.
  2. The cat sensor function can be affected if the unit is on carpeting or a litter mat.
  3. Check that there are no power cords running underneath the base of the robot that might obstruct movement.
  4. If Litter-Robot is on a slippery surface like tile or a wood floor, it may shift over time and come in contact with a wall or furniture.
  5. Make sure your unit is at least one inch away from walls and furniture.
Inspect the litter and waste drawer
  1. Empty the waste drawer. It's best to empty the waste drawer if it's getting close to full.
    Litter-Robot 3: Red Light Flashing (Cat Sensor Fault) (3)
  2. If you use the Whisker app, press Reset Gauge in the Controls section of the app when you empty the waste drawer to reset the waste drawer level in the app.
  3. Check for excess litter inside the globe. Using more than 10 lbs of litter can trigger the cat sensor, causing false cat detects.
  4. Make sure the litter is at or below the raised fill line. Some brands of litter are heavier than others. For these litters, we recommend keeping the litter at least a half inch below the fill line to avoid weight-related errors. Do not use lightweight litter, as this could affect the unit's ability to detect the cat.
    Litter-Robot 3: Red Light Flashing (Cat Sensor Fault) (4)
    Always remember to push the Resetbutton after making changes to the unit. This will recalibrate the weight sensor and circuit board to reflect the changed weight.
  5. From the Home position, press the Powerbutton to turn the unit off.
  6. Press the Powerbutton to turn the unit back on. Litter-Robot will perform an initial Clean cycle, and the cat sensor will take a new measurement of the unit's weight.

Success: The Litter-Robot should return home displaying a blue 'ready light' status.

Unsuccessful: If your unit is not displaying a solid blue light after returning to home position, or cannot complete the cycle, please continue with troubleshooting.

Test the cat sensor
  1. Test the cat sensor by pressing the top of the entryway (not the bonnet) down and away, toward the back of the unit. You should be able to feel a slight spring/bounce movement - this is a good sign that the robot can freely move and that there are no obstructions to prevent the cat sensor from functioning.
  2. From the Home position, press the Resetbutton to zero the weight sensors.
  3. Press the Cyclebutton.

Success: Once the Clean cycle is complete, the unit should go back to blue ready status.

Unsuccessful: If your unit is not displaying a solid blue light after returning to home position, or cannot complete the cycle, you need to replace your base.

Cleaning your Litter-Robot

It's important to deep clean your Litter-Robot every 3 months.

Over time, small clumps can accumulate within the internal pocket of the globe, which can contribute to weight-related errors.

Cleaning or soaking the globe thoroughly every 3 months will help prevent any excess weight from accumulating within the globe.

Customers with more than one cat may want to perform globe cleanings more frequently.

Issue not resolved?

If you've completed this troubleshooting and your Litter-Robot is still flashing red, you need to replace your base.

What do I do?

My unit is covered by WhiskerCare™
If your Litter-Robot is covered by WhiskerCare™ warranty, you have access to replacement parts, at no cost, to get your Litter-Robot up-and-running quickly.Please contact our Customer Experience Team for further assistance.

The warranty on my unit has expired
If your unit is no longer under warranty, we can help you with the necessary parts and instructions to properly fix your unit at home.

Parts Needed (choose one):

  • Litter-Robot 3 Base | Installation Instructions

Need technical support?

Our easy-to-use Troubleshooting Wizard will solve most issues and is the fastest way to get help.

Troubleshooting Wizard

Litter-Robot 3: Red Light Flashing (Cat Sensor Fault) (2025)

FAQs

Litter-Robot 3: Red Light Flashing (Cat Sensor Fault)? ›

Flashing red light

How do you fix a cat sensor fault on a Litter-Robot 3? ›

Check for obstructions that might prevent the cat sensor from functioning.
  1. Make sure Litter-Robot is on a firm, level surface.
  2. The cat sensor function can be affected if the unit is on carpeting or a litter mat.
  3. Check that there are no power cords running underneath the base of the robot that might obstruct movement.

What is a pinch detect fault Litter-Robot? ›

Litter-Robot is equipped with anti-pinch sensors on both sides of the waste drawer chute to ensure your cat's safety while in use. These sensors monitor for potential pinch conditions at all times. If your unit displays a green and white alternating light bar, this indicates an anti-pinch fault during power up.

When to hit reset on Litter-Robot? ›

IMPORTANT: Any time you do anything that affects the weight or placement of the unit, including adding or removing litter, emptying the waste drawer, or moving or cleaning the unit, press the Reset button once you are done.

How to do a hard reset on litter robot 3 reddit? ›

Perform a hard reset after emptying the waste drawer: Unplug Litter-Robot for 10 seconds and replug. Thoroughly clean the Drawer Full Indicator (DFI) with a dry cloth or cotton swab. Check for signs of corrosion.

How do I get my litter robot 3 back online? ›

Re-connecting Litter-Robot 3
  1. Perform a hard reset on your Litter-Robot. Unplug the unit from the back of the base. ...
  2. Ensure you are using the latest version of the Whisker app. ...
  3. Update your network in the Whisker app. ...
  4. Reboot your router. ...
  5. Press both the Cycle and Empty buttons together for approximately 3 seconds.

How do you fix a sensor fault on a Litter-Robot? ›

Inspect the litter and waste drawer

Check for excess litter inside the globe. Using more than 10 lbs of litter can trigger the cat sensor, causing false cat detects. Make sure the litter is at or below the raised fill line. Some brands of litter are heavier than others.

What does cat sensor fault mean? ›

If the timing light is flashing red or you are receiving a "Cat sensor fault" notification in the Whisker app, this indicates the cat sensor has been continuously activated for 30 minutes or more, either by a cat that won't leave the globe or by too much weight in the unit.

What is a cat sensor interrupt Litter-Robot? ›

The Litter-Robot 3 is equipped with a cat sensor that detects when a cat enters and exits the globe. If a cycle is interrupted or the bonnet is removed, the unit will stop, and the yellow light will flash slowly, about 1x per second. This will also occur if the cat sensor is activated by a cat entering the globe.

Why is my Litter-Robot blinking blue when it's not full? ›

Cleaning the DFI sensors

Debris, such as dust or cat fur, can interfere with the DFI sensor. This can cause the unit to inaccurately trigger a drawer-full indication.

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