.

In this way, how do you know if a flame sensor is bad?

Signs of a bad furnace flame sensor are:

1. The furnace lights but then shuts down after a few seconds (short cycles)
2. The porcelain on the flame sensor is cracked.
3. The flame sensor is sooty or corroded.

Also, what causes a flame sensor to go bad? As with any piece of equipment a simple reason could be that dirty flame sensor just goes bad. However a more common reason is that it is just dirty. It is a sensitive sensor so any type of dust or carbon buildup could cause it to malfunction.

Then, do flame sensors wear out?

If no flame is present, the sensor stops or prevents the flow of gas from the gas valve, thus preventing the dangerous situation of gas flowing into the appliance when there is no flame to burn it. Flame sensors and thermocouples are simple parts that wear out and fail over time, and most are easy to replace.

When should I replace my flame sensor?

If the furnace ignition control is seeing a flame current that is within the ignition control's normal range, there is no reason to change the flame sensor unless the flame sensor has a burnt look or it is pitted. If the flame sensor has a normal look, you can just clean it.