Robot mower shows E4 and stops; blades do not spin or stop abruptly when encountering grass.

Safety first: Turn OFF the main power switch and remove the safety key or battery (if accessible). Wait for all moving parts to stop before touching the blades.

Steps to check:

• Clear obstructions: Turn the mower upside down or on its side. Carefully remove any branches, stones, rope, or toys trapped in the cutting disc.
• Inspect blades: Check the Worx pivoting blades for bending, rust, or being stuck. Replace damaged blades and screws as a set.
• Spin test: With power OFF, rotate the cutting disc by hand. It should turn freely with slight resistance. If it is stiff or grinding, the blade motor may be failing.
• Adjust mowing schedule: If grass is very tall or wet, pre‑cut with a conventional mower and schedule shorter, more frequent robot runs to reduce load.
• Reset: After clearing and checking, power ON and start a manual mow. Monitor for recurrence of E4.

When to call a technician: If the disc is free but E4 returns quickly, the blade motor or motor driver on the main board may be defective and should be replaced by a professional.