Litter-Robot 4: Green with partial red flashing or green ping-pong lights (Sensors need cleaning)

  1. Make sure your unit is plugged in.
  2. Make sure your unit is connected and online.
  3. Make sure your firmware is up-to-date. If the app does not give you the option to update, you have the latest version.


Litter-Robot is equipped with OmniSense™ detection. There are three curtain sensors located in the top of the bezel, as well as a weight scale located in the base of the unit. These sensors detect when a cat has entered the unit.

If you see a green ping-pong sequence on the light bar, it means the three curtain sensors are attempting to auto-calibrate their cat detection levels.

This will occur when the unit detects a significant difference between the sensors.

If the auto-calibration passes, the unit will update its dynamic cat sensor threshold values and return back to its previous function, likely a Clean cycle.    

If the auto-calibration fails, the unit will display a green light bar with partial red flashing, which signifies a dirty sensor fault.

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


First, you'll need to inspect specific areas of your Litter-Robot to ensure the sensors are clean.

  1. Let’s take a closer look at the curtain sensors located in the bezel. Any debris near the curtain sensors, such as dust or cat fur, can interfere with these sensors.
  2. This can cause the unit to inaccurately measure the waste drawer level and litter level, as well as cause false cat detects.
  3. Wipe the bezel area where the sensors are located with a dry clean cloth to remove debris such as hair or dust.
  4. Vacuum the inside perimeter of the bezel with a brush attachment, passing over the holes at the top of the bezel where the curtain sensors are located.
  5. You may need to clean the sensors with a cotton swab. Please refer to our Laser sensor cleaning instructions to learn how.
  6. Now, let's run a test cycle. Short press the Reset button, then short press the Cycle button to run a Clean cycle.
  7. After Litter-Robot cycles, it should return to the Home position, displaying a blue light bar.
Successful: If your unit displays a blue light bar, you've been successful. 

Unsuccessful: If you are still seeing a green light bar with partial red flashing, please continue.

Issue not resolved?

Next, you'll need to make sure your firmware is up-to-date.

Whisker can provide updated firmware to your robot with fixes to correct known issues with the unit. We recommend that you always keep your Litter-Robot’s firmware updated to ensure the best possible operation.

Visit our Firmware update instructions to learn how to update your Litter-Robot's firmware.

This may take up to 30 minutes to complete. You will see a single white light blinking on your unit’s control panel while your robot’s firmware is updating

Once the update is complete, your Litter-Robot should be ready for use.

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

Unsuccessful: If you are still seeing a green light bar with partial red flashing after resetting at the Home position, there's likely an issue with your Litter-Robot.

Issue not resolved?

To repair your Litter-Robot, you will need a laser board or a 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):

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