Controller Fault
Generac Failure of generator control module

Display shows 'Controller Fault', 'Internal Error', or is blank/unresponsive while DC power is present.

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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

Internal controller hardware failure, Corrupted firmware, Water intrusion into control panel, Overvoltage damage

How to Fix / Troubleshooting

Safety: Disconnect battery and AC power before removing the controller. Static-sensitive components are inside.

  • Power cycle: Disconnect the battery negative cable for 5 minutes, then reconnect to reset the controller. If the fault clears temporarily but returns, suspect internal failure.
  • Inspect for moisture: Open the control panel and look for signs of water, corrosion, or insect damage. Dry the area thoroughly and correct any enclosure sealing issues.
  • Check harnesses: Reseat all multi-pin connectors to the controller. Look for bent pins or burned traces.
  • Replace controller: If the controller remains unresponsive or continues to show internal fault codes, replace it with the correct Generac control board and perform any required programming.
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Repair Difficulty

Hard 4/5

Required Part

Generator Control Board
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