E9
Granitestone Internal Communication / MCU Error

E9 error code appears and the unit will not power on fully or shuts off quickly.

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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

Corrupted firmware on main control PCB, Failed microcontroller, Shorted low-voltage circuit, Electrostatic or surge damage to PCB

How to Fix / Troubleshooting

Safety first: Unplug the air fryer. Internal electronics can store charge; avoid touching capacitors.

Steps to address E9:

  • 1. Basic reset: Unplug for at least 15 minutes, then plug back in. Try a simple manual temperature/time setting instead of presets.
  • 2. Check for external causes: Ensure the unit is not exposed to excessive moisture, steam, or heat from nearby appliances, which can affect electronics.
  • 3. Inspect the control PCB: Remove the housing and visually inspect the main control PCB for burned spots, cracked components, or corrosion.
  • 4. Reseat connectors: Disconnect and reconnect all harnesses going to the control board (power input, sensor, fan, heater, panel). Poor connections can cause communication errors.
  • 5. Replace the control board: If E9 persists and no obvious wiring issue is found, the microcontroller or firmware is likely damaged. Replace the main control PCB with a Granitestone-compatible part.
  • 6. Surge protection: After repair, consider using a surge-protected outlet strip to reduce the risk of future MCU damage.
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Repair Difficulty

Hard 4/5

Required Part

Main Control PCB
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