Could be ignitor, pressure switch, high limit, thermostat, etc. It has to be opened to be checked.

what did you do to fix it? I'm in the same boat. thank you.

I hate when people never come back with a fix

Lorna, Did you fix the heater? My is doing the same thing

There is a manual that can help

that was stupid

This one is too easy. Its a bad control board behind the knobs.