Robot vacuum stops and displays E4 or announces a cliff sensor error; may refuse to move or constantly backs up even on flat floors.

Safety first: Turn OFF the robot and remove it from the dock. Do not look directly into any infrared LEDs at close range.

• 1. Locate cliff sensors: On the underside front edge of the robot, identify the small dark windows (usually 3–4) that house the cliff sensors.
• 2. Clean sensor windows: Use a soft, dry microfiber cloth to gently wipe each sensor window. If there is sticky residue, lightly dampen the cloth with water or isopropyl alcohol and wipe again. Do not spray liquid directly on the robot.
• 3. Inspect for damage: Check for deep scratches, cracks, or cloudiness on the sensor windows. Physical damage can cause false cliff readings.
• 4. Reset and test: Power ON the robot and place it on a flat, light-colored floor away from edges. Start a cleaning cycle and observe whether it still reports a cliff error.
• 5. Check wiring (advanced): If comfortable opening the unit, remove the bottom cover and verify that the cliff sensor harness is firmly connected to the main PCB and that no wires are pinched or broken.
• 6. Replace sensor module: If cleaning and wiring checks do not resolve E4, replace the iHome cliff sensor array or individual cliff sensor module specified for your model.