Robot lawnmower shows E3 and stops; wheels do not move even though blades may spin.

Safety first: Turn off the main power and keep the mower on a stable surface. Avoid working on slopes.

• Check for obstructions: Inspect both rear drive wheels for stones, branches, or wire wrapped around the axles. Remove any debris and ensure the wheels turn freely by hand.
• Inspect wheel treads: If the Hyundai drive wheels are packed with wet grass or mud, clean the treads thoroughly to reduce load.
• Verify slope: Confirm the mower is not operating on slopes steeper than the maximum gradient specified in the Hyundai manual. Relocate the boundary wire if necessary.
• Check drive motor connectors: With power OFF and battery disconnected, remove the top cover and locate the left and right drive motor connectors on the main PCB. Ensure they are firmly seated.
• Test each wheel: Manually rotate each wheel. If one feels rough or locked, the drive motor/gearbox assembly is likely failing and should be replaced.