E12
Heatrae Sadia
Temperature Calibration / Sensor Mismatch Error
Heatrae Sadia digital water heater intermittently shows E12 and water temperature fluctuates.
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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
Incorrect sensor type fitted, Loose sensor connections, Firmware expecting different sensor curve, Partial sensor failure
How to Fix / Troubleshooting
Safety first: Turn off power before accessing sensors or the PCB.
Steps to address E12:
- 1. Confirm correct parts: Check service records or part numbers on the NTC sensors. Ensure genuine Heatrae Sadia sensors of the correct specification are installed.
- 2. Inspect connections: Reseat all temperature sensor connectors on the PCB. Ensure no two sensors are cross-connected.
- 3. Compare readings (for competent persons): With power off, measure resistance of inlet, outlet, and cylinder sensors at the same temperature. Values should be consistent with the manufacturer’s chart.
- 4. Replace suspect sensors: If one sensor reads significantly different from the others at the same temperature, replace it.
- 5. Professional recalibration: Some models may require a service engineer to enter a calibration or configuration mode after sensor replacement.
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Repair Difficulty
Hard
4/5
Required Part
Temperature Sensors Set
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