Set Appliance State:
Gas Off
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Measurement:
Measure resistance across the exposed terminals of the sensor.
Note: Resistance measured will vary according to the boiler temperature the cooler the boiler the higher the resistance. The resistance should conform to the table below.
Reconnect leads after test.
Note: Resistance measured will vary according to the boiler temperature the cooler the boiler the higher the resistance. The resistance should conform to the table below.
| Temperature °C | Resistance in kOhms |
| 10-20 | 20.0-12.5 |
| 20-30 | 12.5-8.0 |
| 30-40 | 8.0-5.2 |
| 40-50 | 5.2-3.5 |
| 50-60 | 3.5-2.4 |
| 60-70 | 2.5-1.7 |
| 70-80 | 1.7-1.2 |
