Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Disconnect wires from return thermistor (rear thermistor)
Measurement:
Measure the resistance between the two pins for the return sensor.
RESISTANCE RETURN SENSOR
Resistances vary with temperature and should conform approximately to the table below:
| Temperature Range (°C) | Resistance Range |
|---|---|
| 0°C to 10°C | 18.0kΩ - 28.0kΩ |
| 10°C to 20°C | 12.0kΩ - 18.0kΩ |
| 20°C to 30°C | 8.3kΩ - 12.0kΩ |
| 30°C to 40°C | 5.7kΩ - 8.3kΩ |
| 40°C to 50°C | 4.1kΩ - 5.7kΩ |
| 50°C to 60°C | 3.0kΩ - 4.1kΩ |
| 60°C to 70°C | 2.2kΩ - 3.0kΩ |
| 70°C to 80°C | 1.7kΩ - 2.2kΩ |
| 80°C to 90°C | 1.3kΩ - 1.7kΩ |
| 90°C to 100°C | 1.0kΩ - 1.3kΩ |
Note: Clicking on the resistance table will switch between table and graph view.
Isolate as per TOPs P4
and refit as necessary