E20
LG Internal Bus / Module Communication Fault

Robot vacuum reports an internal communication error (E20); multiple subsystems fail simultaneously.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Loose internal harness between main PCB and sensor boards, Oxidized connectors, Partial main PCB failure, Overvoltage event damaging communication lines

How to Fix / Troubleshooting

Safety first: Disconnect the robot from the dock and remove the battery before unplugging internal connectors.

  • 1. Hard reset: Perform a full power cycle and factory reset to rule out software glitches.
  • 2. Open housing (advanced): Remove the top or bottom cover to access the main PCB and internal harnesses.
  • 3. Reseat connectors: One by one, unplug and firmly replug the ribbon cables and harnesses connecting the main PCB to wheel modules, sensors, and the fan. Inspect for corrosion or bent pins.
  • 4. Visual inspection: Look for burnt components or damaged traces on the main PCB.
  • If communication errors continue after reseating connectors, the main PCB or one of the attached modules may be defective and should be diagnosed with service tools or replaced.
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Repair Difficulty

Professional Required 5/5

Required Part

Main PCB Harness Assembly
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