E104
GSW
Thermostat / Sensor Stuck Closed
GSW electric water heater with digital display shows E104 and water is excessively hot
Advertisements
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.
Advertisements
Possible Causes
Failed electronic thermostat, Shorted temperature sensor, Miswired control, Stuck relay on control board
How to Fix / Troubleshooting
Safety: Risk of scalding. Turn off power at the breaker immediately.
- Verify set temperature: Check the digital setpoint and reduce it to 49–54°C (120–130°F).
- Inspect sensor wiring: Ensure the tank temperature sensor is properly attached and wiring is intact.
- Test thermostats (if mechanical backup): On some models, mechanical thermostats back up the electronic control. Verify they open when water is hot; replace if they remain closed.
- Replace faulty control: If E104 persists and water overheats, the electronic control or sensor is likely defective and should be replaced with a GSW-approved kit by a qualified technician.
Advertisements
Repair Difficulty
Hard
4/5
Required Part
Electronic Thermostat / Control
Check Price on Amazon
We may earn a commission from links on this page.
Advertisements