Robot vacuum reports E04 and stops near edges or stairs; may refuse to move forward.

Safety first: Turn the robot OFF. Do not test near actual stairs until the error is resolved.

• 1. Locate cliff sensors: On Bosch robot vacuums, cliff sensors are usually on the underside at the front edge (small dark windows).
• 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, then dry thoroughly.
• 3. Check for physical damage: Inspect the plastic windows for cracks, deep scratches, or cloudiness. Damage can cause false cliff readings.
• 4. Move to a bright, flat area: Place the robot on a light‑colored, flat floor (no dark rugs or patterns that resemble holes) and start a cleaning cycle. Dark carpets can sometimes trigger cliff sensors.
• 5. If E04 persists: The cliff sensor module or its wiring may be faulty. Internal access requires opening the housing and should be done only by a qualified technician to avoid damaging the mainboard.