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Furnace ignites and runs for a short time, then burner shuts off. No codes
If no codes then it is one of 2 things...either the thermostat is turning power off to the W connection at circuit board..Or the circuit board is bad.A fault with the gas valve would result in a code.To test...remove the thermostat and take the wire from R and the wire from W and twist together. If furnace runs without stopping replace thermostat.If the furnace faults with blink code then it is bad circuit board.
Thanks! cleaned flame sense rod and furnace runs correct.
Excellent. Thanks for your patience.