Replacement parts need to buy flame sensor

When the t'stat starts the furnace, 1st the draft inducer motor runs for a few seconds, then the igniter glows and the gas valve opens.
The burner then lights, the igniter shuts off. If the burner shuts off when the igniter shuts off, then it's the flame sensor. 1st disconnect the power, remove the flame sensor and clean it with some 000 steel wool or scotch brite and reinstall it. 95% of the time that will fix it, otherwise you will need to replace the flame sensor.

This could be the flame sensor. If you can look into the firing chamber there should be a steel rod about 5" long that dangles into the gas fire jets. Turn off the unit. If you take the fire sensor out and gently rub it with steel wool and replace it, it may start working again. If it does, great, but order a new fire sensor and replace the old one when it comes in. They are very cheap.

You will need the make and serial of you appliance from that you can get the part you need from a stockiest

Does the unit have a flame sensor? Check manual. Flame sensors get corroded and need cleaned or replaced. I have had success cleaning them but when you can buy a new flame sensor

With the limited information provided above, I would say that it is your flame rectifier (flame sensor).
If the heater ignites, and the flame sensor is bad, it will go out right away as a safety precaution.

Below is the parts/troubleshooting manual for this heater. You can find the part number for your flame sensor, and replace it.

http://www.pentairpool.com/pdfs/MaxEThermOM.pdf

Your igniter is working fine. The problem is the flame sensor needs to be replaced. The flame sensor is a safety feature. If it doesn't detect heat from the igniter it prevents the gas from flowing. A new flame sensor will cost about 30 - 35 dollars. You can buy on online here

Your easiest (cheapest) starting point is with the thermistor (flame sensor).
You can easily check that it is in direct contact with the pilot... and at the same time - check the ignitor is sparking

1. Check for ignition - if not igniting - replace ignitor.
2. Check/clean Flame sensor - if pilot is lit - replace the sensor.
3. If voltage at the gas valve checks out (from flame sensor) - gas valve should be replaced.


CLICK HERE to see the available parts if one of them is not working properly.

Do the burners come on? If so then yes it probably is the flame sensor if not then there is another issue not the flame sensor. The flame sensor could just be dirty take the flame sensor out and clean it with a piece of emery cloth or lite sand paper and put it back in and this should get the burners to stay on.

The flame sensor is bad. Go to repair clinic. com and put in the model and it will pullup the parts for your oven. Buy the flame sensor. It has to 'see' the gas flame to remain open from the gas valve.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/craig_3fa289bf857b1a3c

The flame sensor is not sensing flame. If it is a thermocouple sensor, they can be purchased for 6 bucks and replaced in 15 min.

Some units have a different type of flame sensor and are a part of the ignitor assembly. In that case, the ignitor assembly would have to be replaced. Those usually run 20 to 60 bucks.

There is a remote possibility that the sensor and pilot flame shroud need to be cleaned, due to rust and other corrosion preventing the flame from properly contacting the sensor. You can try cleaning that first, but chances are you will simply have to replace the sensor.