Litter-Robot 4: Bonnet Removed and Yellow-Purple LED Bar - Diagnosis

⚠️ SAFETY WARNING. The Litter-Robot 4 operates with a low-voltage power supply (15V DC). Before removing the bonnet or globe, it is crucial to unplug the power supply from the wall outlet or from the back of the device. This prevents the risk of accidental short circuits on the delicate electronic boards (Main PCB and laser sensor board) and avoids sudden motor activation (mechanical risk of hand injuries). If you do not feel confident, it is recommended to rely on a qualified technician. ReeFix provides this diagnosis EXCLUSIVELY for educational and informational purposes.

QUICK TEST

Is your Litter-Robot 4 reporting "Bonnet Removed" in the app and showing an abnormal light? Let's clarify the signals:

• Flashing Yellow LED Bar: This is the official signal for "Bonnet Removed."
• Alternating Yellow-Purple LED Bar: Indicates that the robot has entered "Scale Calibration Mode" or "Audit Mode" (often due to inadvertently pressing a key combination during reset attempts).

To resolve both issues, follow this verification sequence:

1. Unplug the power supply to work in complete safety and avoid short circuits.
2. Check the optical bonnet sensor:
   • Unlike previous models, the Litter-Robot 4 detects the bonnet via an optical (light) sensor located inside a small hole on the rear bezel, positioned at 1 o'clock (immediately to the right of the central attachment slot).
   • The bonnet has a dedicated plastic tab that, when correctly inserted, enters this hole and blocks the light. If the sensor detects light, the app reports "Bonnet Removed."
   • Check that this tab on the bonnet is not bent, deformed, or broken.
   • Clean the sensor hole on the bezel with a dry cotton swab to remove any litter dust that might falsify the reading.
3. Reposition the bonnet precisely:
   • First, insert the rear tabs of the bonnet into the corresponding slots in the base.
   • Lower the bonnet onto the globe and press firmly on the sides until you hear a double "click" from the side latches.
   • Gently push down on the upper central part as well to ensure the front tab fits perfectly into its housing and covers the optical sensor.
4. Clean the OmniSense laser sensors:
   • Very fine litter dust (bentonite) can settle on the three Time-of-Flight (ToF) laser sensors located in the upper inner part of the bezel.
   • Use a can of compressed air for cleaning your Litter-Robot 4 to gently blow away dust from the three sensor slots. Keep the can at a safe distance to avoid excessive pressure.
   • Wipe the external surface of the sensors with a dry, clean microfiber cloth.
5. Reconnect power and perform a reset:
   • Reconnect the plug. If the LED bar still shows the alternating yellow-purple pattern (Audit Mode), unplug the power supply again, wait 10 seconds, and reconnect it without pressing any buttons to allow for a standard restart.
   • Once started, press the Reset button on the control panel to calibrate the weight sensors.

DECISION FORK

Quick Test Result:

• Case A: The error disappears after correct bonnet positioning and cleaning.

  • Probability: Very high (about 80% of cases).
  • Decision: REPAIR YOURSELF. The problem was simply a mechanical misalignment or dust on the optical sensor. No spare parts needed. Cost: €0 - €10 (for eventual purchase of compressed air).
  • Why: The bonnet easily shifts during maintenance or if bumped by cats, interrupting the optical sensor's obscuration.

• Case B: The error persists, or the plastic tab of the bonnet is broken or deformed.

  • Probability: Medium (about 15% of cases).
  • Decision: CONTACT A TECHNICIAN or REPLACE THE BONNET. If the bonnet tab is damaged, the bonnet must be replaced. If the bonnet is intact but the internal optical sensor no longer detects closure, there might be a wiring or sensor board issue.
  • Estimated cost: An original replacement bonnet costs about €110. If the intervention requires replacing the wiring or internal optical sensor by a technician, estimate about €30-€60 for labor, plus the eventual use of isopropyl alcohol for cleaning internal Litter-Robot 4 contacts (about €10-€15).

• Case C: The LED bar continues to flash alternating yellow-purple or the robot shows erratic behavior (unresponsive to commands, continuous restarts).

  • Probability: Low (about 5% of cases).
  • Decision: CONTACT A TECHNICIAN. If restarting does not eliminate the yellow-purple alternation, the motherboard might be stuck in test mode or have a hardware defect. An unstable power supply can also cause voltage anomalies.
  • Estimated cost: An original power supply for Litter-Robot 4 costs about €25-€35. If the problem lies in the motherboard (Main PCB) or the laser sensor board, component replacement ranges from €100 to €200. As this is a high-end device (worth over €700), electronic repair is always highly recommended and cost-effective compared to buying a new robot.

DIAGNOSIS CONFIRMED

The main cause (50%) of the "Bonnet Removed" error on the Litter-Robot 4 is the failure to obscure the optical presence sensor. This sensor, located in the bezel at 1 o'clock, must be completely covered by the bonnet tab. If the bonnet is not perfectly latched or if the tab is deformed, ambient light penetrates the hole, activating the safety feature that blocks the rotation cycle to protect the cat.

Another 30% of cases are related to bentonite dust accumulation on the OmniSense laser sensors. Although these ToF sensors measure the cat's distance and litter level, severe obstruction can crash the safety system, leading to generic lockout errors or interfering with correct bonnet initialization.

In 15% of cases, the error is electrical in nature: a loose connection or oxidation of the internal wiring connecting the upper sensor board to the main motherboard (Main PCB). Rotation vibrations can loosen connectors over time.

Finally, the remaining 5% is caused by a defective power supply that does not provide stable 15V DC under load, or a firmware loop (indicated by the alternating yellow-purple bar) requiring a hardware reset or motherboard replacement.

Output for technician: The device, a Litter-Robot 4, exhibits a cycle blockage with "Bonnet Removed" notification and/or alternating yellow-purple LED bar. Required: verification of the bonnet's obscuring tab integrity, cleaning of the optical sensor at 1 o'clock on the bezel, cleaning of the OmniSense ToF laser sensors, and checking wiring continuity to the Main PCB. Verify 15V DC power supply stability under load.

Final operational decision: If cleaning the optical sensor and repositioning the bonnet resolves the error -> REPAIR YOURSELF; if the bonnet has broken tabs or the internal sensor is faulty -> REPLACE THE BONNET or CONTACT A TECHNICIAN; if the system remains stuck in calibration mode (yellow-purple) or exhibits electronic anomalies -> CONTACT A TECHNICIAN for replacement of the sensor board or Main PCB, an intervention that is largely cost-effective given the high value of the device.