Gas Furnace Lights only for 8 Seconds then Turns Off after Cleaning Flame Sensor. Help!

My gas furnace is set to heat and the flame only ignites for 8 seconds or so and then turns off.

[@Bender260]

Check your filter(clogged airflow can do this) and your limit switch, and your flame sensor. I know you just cleaned it, there's a possibility it is malfunctioning instead of dirty.

[@realSamAndrew]

Check your pressure switch, high limit switch, gas valve pressure. Get a piece of heavy solid copper wire and use it as a test replacement for the flame sensor. If it still happens, it's something else. Please come back and report the ultimate cause and fix when you solve it.

[@HoaNguyen-ui4nc]

There are two things you need to check. First the thermostat, do it still stay on when the the flame on. Second, if you said that you clean the flame sensor already then i am really sure that your control board is bad.