How to Fix / Troubleshooting

Safety first: Isolate electrical power before removing covers or touching wiring.

Steps to address E05:

1. Locate inlet sensor: Remove the cover and identify the NTC sensor on the cold water inlet pipe or manifold. It may be clipped or strapped to the pipe.
2. Check mounting: Ensure the sensor is firmly attached and making good thermal contact with the pipe. Refit any clips or thermal paste as originally installed.
3. Inspect cable: Follow the sensor cable to the PCB. Look for kinks, cuts, or crushed sections. Reseat the connector at the PCB.
4. Resistance test: With power off, disconnect the sensor and measure its resistance. Compare to the manufacturer’s chart. Replace the sensor if readings are out of range.
5. Test operation: Reassemble, restore power, and run a hot tap. If E05 persists with a known-good sensor, the PCB input channel may be faulty and will require professional diagnosis.

Heatrae Sadia digital water heater shows E05 and shuts down when a hot tap is opened.

Possible Causes