Robot vacuum beeps and reports E1; unit will not start cleaning and may say the drop sensors are dirty or the robot is near a ledge even on flat floor.

Safety first: Turn the robot OFF using the power switch (if present) and remove it from the charging base. Do not work on the robot while it is charging.

Step-by-step:

• Clean the cliff sensors: Turn the robot upside down on a soft surface. Locate the small dark windows along the front underside (usually 3–6 sensors). Wipe each window gently with a dry microfiber cloth. If there is sticky dirt, lightly dampen the cloth with water or isopropyl alcohol and dry thoroughly.
• Check for physical damage: Inspect each sensor window for cracks, deep scratches, or missing plastic. If damaged, the cliff sensor module will likely need replacement.
• Test on a bright, flat surface: Place the robot on a light-colored, flat floor away from edges. Power it on and start a cleaning cycle. Avoid dark rugs or black tape, which can be interpreted as a drop.
• Reset the robot: On many Eufy models, press and hold the power or start button for 10–15 seconds to reboot. Consult the user manual for model-specific reset instructions.
• Internal inspection (advanced): If E1 persists, remove the bottom cover (usually several Phillips screws) and locate the cliff sensor harnesses going to the main PCB. Ensure all connectors are fully seated. If a sensor board is visibly burned or corroded, replace the cliff sensor assembly.

When to stop: If the robot still reports E1 after cleaning and rebooting, and you are not comfortable opening the unit, contact Eufy support or a professional technician for sensor module replacement.