E008
GSW
Temperature Sensor Out of Range (Overtemperature)
GSW gas water heater shows E008 and shuts down with very hot water at the taps
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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
Failed NTC temperature sensor, Shorted sensor wiring, Gas valve stuck open, Incorrect thermostat calibration
How to Fix / Troubleshooting
Safety: Risk of scalding. Turn the gas control to OFF and allow the water to cool before working on the heater.
- Check temperature setting: Verify the set temperature on the gas control is not above recommended levels. Adjust to 49–54°C (120–130°F).
- Inspect sensor wiring: Locate the tank temperature sensor (often inserted into a well or attached to the tank). Check for damaged insulation, loose connectors, or corrosion. Repair or reconnect as needed.
- Test sensor (advanced): A technician can measure the resistance of the NTC sensor and compare it to GSW specifications at a known water temperature. Replace the sensor if readings are out of range.
- Evaluate gas control valve: If water continues to overheat despite a correct sensor, the gas control valve may be sticking open and must be replaced immediately by a professional.
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Repair Difficulty
Hard
4/5
Required Part
Tank Temperature Sensor (NTC)
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