Robot lawnmower displays E03 and stops; wheels may twitch but mower does not move.

Safety first: Turn OFF the main power switch and remove the mower from the lawn. Avoid placing fingers near wheels when power is on.

• Inspect drive wheels: Check both left and right wheels for wrapped grass, roots, or twine. Remove any debris from the wheel treads and axle area.
• Check wheel movement: With power OFF, rotate each wheel by hand. They should turn smoothly with some gearbox resistance but no binding. A wheel that is locked or very stiff indicates a gearbox or bearing issue.
• Clean wheel housings: Use a brush or compressed air to clear dirt from around the wheel motors and housings.
• Check wiring: Remove the top cover and verify that the left and right drive motor connectors are fully seated on the mainboard and free of corrosion.
• Test operation: Turn power ON and start a manual mow. Observe whether one or both wheels attempt to move before E03 appears.

If one wheel consistently fails to move or E03 appears immediately, the corresponding drive motor assembly or mainboard motor driver is likely defective and should be replaced.