Wyze robot vacuum displays C9 and will not start; often associated with internal communication or sensor bus errors.

Safety first: Turn off the robot, remove it from the dock, and allow it to sit for 1–2 minutes before troubleshooting.

• Power cycle: Turn the robot off, wait 60 seconds, then turn it back on. Sometimes a transient communication error clears with a full reboot.
• Check for obvious damage: Inspect the exterior for impact damage or signs of liquid exposure. If the robot has been wet, do not attempt to power it repeatedly; seek professional service.
• Update firmware: Use the Wyze app to check for and install any available firmware updates, which can resolve some communication issues.
• If C9 continues: Internal diagnostics and board-level checks are required. This involves opening the robot and checking ribbon cables and harnesses between the main board and sensor modules. Because of the risk of further damage, this should be done by Wyze support or a qualified technician.