Robot lawnmower shows E16 Ultrasonic Sensor Error (on models with obstacle sonar); mower fails to detect obstacles or stops with error.

Safety first: Turn OFF the mower and remove the battery before cleaning or servicing sensors.

• Clean sensor faces: Locate the ultrasonic sensors on the front or sides of the NAC mower. Wipe the plastic lenses with a soft, damp cloth and dry them.
• Inspect for cracks: Check the sensor housings for cracks or signs of impact that may have allowed water inside.
• Check wiring: Remove the front cover and trace the ultrasonic sensor harness to the main PCB. Ensure all connectors are fully seated.
• Test operation: After reassembly, power ON and place a large object (e.g., a box) in front of the mower. Start a test run and observe if it detects the obstacle.
• Replace sensor: If E16 persists and the mower does not respond to nearby obstacles, replace the NAC ultrasonic sensor module.

Warning: Do not use solvents or abrasive cleaners on sensor lenses; they can damage the surface and reduce performance.