I'm having this too and cleaned the flame sensor and unplugged replugged the connections. Sometimes when I turn on the furnace nothing happens. Then after a while the inducer motor comes on and goes off over and over and then the LED blinks, sometimes with a code 22 and other times with a single blink or two fast blinks which makes no sense or has no code. I have no gas leak that I can smell - should I just replace the PC board? it's from 96 so is 17 years old. What else should I try?