How Do You Test A Flame Sensor Signal?
To test a flame sensor signal, you will need a multimeter or a voltmeter. First, turn off the power supply to the furnace and locate the flame sensor. Remove the flame sensor from the furnace and clean it with a soft brush or sandpaper to remove any dust or debris. Reconnect the flame sensor to the furnace and turn the power supply back on. Start the furnace and measure the voltage between the flame sensor and the furnace’s ground using the multimeter or voltmeter. A working flame sensor will produce a small voltage signal (around 50 millivolts) when there is a flame present. If the voltage reading is erratic or zero, the flame sensor may need to be replaced.