Litter-Robot 4 Troubleshooting

Likely causes

• A cycle is paused because the cat sensor is still triggered.
• The unit is in the middle of its post-visit countdown.
• Something is resting on the globe and holding the weight sensor active.

Fix it, in this order

1. Wait out the countdown. A pulsing blue light during the delay period is normal behaviour, not a fault.
2. Clear the top of the unit. A towel, a cat bed or a second cat sitting on the bonnet will hold the sensor triggered indefinitely.
3. Reset by power cycle. If blue persists with nothing on the unit, unplug for 30 seconds.

Likely causes

• The globe is obstructed or has not returned to its home position.
• The drawer is out or not fully seated.
• Over-torque protection has tripped, usually from packed or overfilled litter.

Fix it, in this order

1. Power off and inspect. Unplug, remove the globe, and look for a jam at the sifting screen or the drop zone.
2. Reduce the litter. Remove litter down to the fill line before restarting. Over-filling is the usual cause of an over-torque trip.
3. Reseat and restart. Refit the globe, seat the drawer until it clicks, then plug in and let it home itself.

Likely causes

• The waste drawer is full.
• The drawer is not seated.
• The drawer sensor is dusty and reading full.

Fix it, in this order

1. Empty and reseat. Empty the drawer, wipe the sensor window, and push the drawer home until it clicks.
2. Reset the counter. Press and hold the reset so the fill count clears.

Likely causes

• The cat re-entered mid-cycle. This is the safety system doing its job.
• A clump has jammed against the sifting screen.
• The unit is on an unstable surface and the weight reading fluctuates during rotation.

Fix it, in this order

1. Confirm it is not the cat. Check the app cycle log. An interruption immediately followed by a visit entry is normal safety behaviour.
2. Clear the screen. Power off and scrape any welded clump from the screen and drop zone.
3. Stabilise the base. Move the unit off carpet or a flexing floorboard onto a solid, level surface.

Likely causes

• Too much litter. Overfilling past the fill line is the single most common cause of a failed cycle.
• A clump has welded to the sifting screen or the drum wall and is jamming rotation.
• The waste drawer is not seated fully, so the safety interlock keeps the motor disabled.

Fix it, in this order

1. Check the litter level. Litter should sit at or just below the marked fill line. If in doubt, remove a cup and try again.
2. Reseat the drawer. Pull the waste drawer fully out and push it back until it clicks. A drawer that is 5 mm proud will stop the cycle.
3. Clear the screen. Power off, remove the globe or drum, and scrape any welded clumps off the sifting screen with a plastic scraper.
4. Run an empty test cycle. With the litter removed, run one cycle. If it completes empty and fails when loaded, the problem is litter or weight, not the motor.

Likely causes

• The unit is not on a level floor. Weight sensing assumes level.
• Litter has been added or removed without re-taring, so the baseline is stale.
• Something is resting against the unit — a wall, a mat edge, a cable — and taking part of the load.

Fix it, in this order

1. Level it. Use a phone level on the base. Even a small tilt on an uneven floor throws readings off by a pound or more.
2. Re-tare after every litter change. Run the calibration or re-zero routine in the app whenever you add or fully change litter.
3. Give it clearance. Leave two inches around the unit and keep it off thick rugs, which flex under load.
4. Separate similar cats manually. Weight-based identification cannot reliably separate two cats within about a pound of each other. Tag visits by hand if that is your situation.

Likely causes

• Waste is packed against the sensor window rather than spread across the drawer.
• The sensor window is dusty. Litter dust builds a film that reads as full.
• The liner is bunched up over the sensor.

Fix it, in this order

1. Wipe the sensor window. Find the small clear window inside the drawer bay and wipe it with a dry microfibre cloth. Do this monthly.
2. Reset the drawer count. Use the reset in the app or the physical drawer button so the counter clears after emptying.
3. Fit the liner flat. Tuck the bag so it lies against the drawer walls rather than ballooning across the sensor line.

Likely causes

• The box is on a 5 GHz network segment. Almost every litter box on the market is 2.4 GHz only.
• The router moved the unit to a different band after a firmware update or a mesh node reshuffle.
• The box sits behind an appliance or in a metal-lined cabinet that kills the signal.

Fix it, in this order

1. Check the band. Confirm your phone is on the 2.4 GHz network when you pair. On a combined-band router, temporarily split the bands or use the guest 2.4 GHz network.
2. Power cycle in order. Unplug the box for 30 seconds, then reboot the router, then plug the box back in. Order matters — the box looks for the network on boot.
3. Move it 3 feet. Signal strength at floor level behind a washing machine is far worse than it looks. Try the unit in the open before concluding the radio is faulty.
4. Re-pair from scratch. Remove the device from the app entirely, then run setup again rather than retrying the existing entry.

Likely causes

• Phone is on 5 GHz while the box needs 2.4 GHz.
• The Wi-Fi password contains characters the unit rejects, or the network name is hidden.
• Location or local-network permission is denied to the Whisker app, so it cannot see the device.

Fix it, in this order

1. Grant the permissions. Both Location and Local Network permissions must be allowed for pairing to work on iOS. Android needs Location.
2. Use a simple 2.4 GHz SSID. Broadcast a plain, visible 2.4 GHz network with an alphanumeric password for setup. You can move it afterwards.
3. Stay within six feet during pairing. Pairing uses a short-range handshake before the box joins the network.

Likely causes

• The carbon filter is past its life. Filters degrade quietly; there is no warning.
• The drawer gasket has litter dust on the seal face, so the drawer no longer closes airtight.
• Litter depth is too shallow, so urine reaches the drum wall instead of clumping.
• The unit needs a full wash. Waste film builds on the drum wall and no amount of cycling removes it.

Fix it, in this order

1. Replace the filter. Set a recurring reminder rather than waiting to notice. Whisker filters are a running cost, not an optional accessory.
2. Clean the gasket. Wipe the drawer seal and the mating face with a damp cloth, then dry. A gritty seal leaks.
3. Deepen the litter. Run to the fill line, not below it. Shallow litter is the most common cause of odor in an otherwise healthy unit.
4. Full wash every 4-6 weeks. Strip the unit, wash the drum and drawer with unscented soap and warm water, dry completely before reassembly.