E13 appears; unit beeps and stops, often when switching between floor and tool mode.

Safety first: Unplug the machine before accessing internal valves or switches.

• Operate the selector several times: Move the floor/tool mode selector back and forth to free any minor sticking.
• Check external linkage: Ensure the selector knob is not cracked and that it properly engages the internal mechanism.
• Inspect diverter valve: Open the housing and locate the solution diverter valve. Check for debris or scale preventing movement. Clean gently and lubricate with a food-grade silicone lubricant if recommended.
• Test selector switch: Use a multimeter to verify that the mode switch changes state when toggled. Replace if faulty.
• Check diverter motor (if motorized): Confirm the motor receives voltage when changing modes. Replace the diverter motor assembly if it does not move and is receiving power.