COMM ERROR
OpenEVSE
Serial Communication Failure
Display shows 'COMM ERROR', Wi-Fi module not responding, or LCD shows communication fault between boards.
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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 serial cable between main board and Wi-Fi module, Incorrect baud rate or firmware mismatch, Damaged ESP8266/ESP32 Wi-Fi module, Faulty UART driver on main board
How to Fix / Troubleshooting
Safety first: Turn off power before unplugging or plugging any internal modules.
- Step 1 – Reseat connectors: Open the enclosure and locate the Wi-Fi module (ESP8266/ESP32) and its serial header. Gently unplug and replug the module to ensure a solid connection.
- Step 2 – Inspect for damage: Look for bent header pins, burn marks, or cracked components on the Wi-Fi module and main board.
- Step 3 – Firmware compatibility: Verify that the Wi-Fi firmware version is compatible with the main board firmware. Update both to the latest recommended versions from OpenEVSE.
- Step 4 – Test without Wi-Fi: Temporarily remove the Wi-Fi module and see if the EVSE operates normally using only the LCD. If so, the Wi-Fi module is likely defective and should be replaced.
- Step 5 – Replace module or board: If reseating and firmware updates do not resolve the issue, replace the Wi-Fi module. If the problem persists, the UART on the main board may be damaged and the board should be replaced.
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Repair Difficulty
Medium
3/5
Required Part
Wi-Fi Module (ESP8266/ESP32)
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