Robot lawnmower shows E4 and refuses to start mowing; often occurs when starting near a slope or obstacle.

Safety first: Switch OFF the mower and remove power from the charging station before moving it.

• Relocate mower: Move the mower to a flat, level area of the lawn. Ensure it is not resting on a slope, mound, or wheel rut.
• Check maximum slope: Verify that the area where the mower operates does not exceed the maximum incline specified in the Einhell manual (typically around 35%). Adjust boundary wire to exclude steeper zones.
• Inspect tilt sensor: Open the top cover according to the service instructions. Locate the tilt sensor (often a small module or ball‑type sensor on the mainboard). Ensure it is firmly mounted and not loose. Do not solder or modify unless you are experienced.
• Clean interior: Remove dust and grass from around the sensor and mainboard using dry compressed air. Moisture or debris can cause false tilt readings.
• Reassemble and test: Refit the cover, ensure all screws are tight, and restart the mower on level ground. If E4 persists, the tilt sensor or mainboard may require replacement.