Cause of error code #W03

Blinking Screen – Press “Reset” key to view this message

- DHW Sensor Shorted

Solution for error code #W03

- Check wiring connection to DHW Sensor.
- Remove the wires from terminals #5 and #6 on the boiler and check the resistance between them.
- If this reading is below 1000 Ω, check the reading at the sensor
- If the reading is the same at the sensor, replace the sensor.
- If the reading is higher at the sensor, replace the wiring.