Robot displays F16 and may not detect or drive the side brush (if fitted).

Safety first: Turn the robot OFF and flip it over on a soft surface.

• Remove side brush: Unscrew or unclip the side brush from its hub.
• Clear debris: Remove hair and fibers from the base of the hub and around the spindle.
• Spin test: Rotate the side brush motor shaft by hand. It should turn with some resistance but not be seized. If it is locked, the module may need replacement.
• Reinstall or replace brush: Refit the cleaned brush or install a new genuine Dyson side brush if the old one is bent or damaged.

If F16 continues and the side brush never turns, the side brush motor assembly is likely faulty.