E11
Yamaha AC Overvoltage Protection

Generator shuts down and shows E11 after running under load.

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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

Faulty AVR (Automatic Voltage Regulator), Incorrect AVR sensing wiring, Loose or broken neutral reference, Defective alternator excitation circuit

How to Fix / Troubleshooting

Safety first: Isolate the generator from the building via the transfer switch and disconnect battery negative. High voltage is hazardous; use a true-RMS meter rated for the voltage.

  • Measure output voltage: With the generator running in MANUAL and no load (if it will run), measure line-to-line and line-to-neutral voltages. Compare to Yamaha specifications.
  • Inspect AVR connections: Locate the AVR in the alternator terminal box. Check all sensing and output wires for tightness and signs of overheating. Reseat connectors.
  • Check neutral bond: Ensure the alternator neutral connection is secure and not floating due to a loose lug.
  • Replace AVR: If voltage is unstable or consistently high and wiring is intact, replace the AVR with the correct Yamaha part number for your alternator.
  • Retest under load: After replacement, run the generator and gradually apply load while monitoring voltage. Clear E11 and confirm normal operation.
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Repair Difficulty

Hard 4/5

Required Part

Automatic Voltage Regulator (AVR)
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