I have a Heil Natural Gas Furnace with smart valve sv9541 that goes off and the valve click as the ignitor glows on and off while lighting the pilot light which then goes out, and back lit?Is this a flame sensor problem?
Thanks for advice.

Its possible you have a dirty flame sensor you can try cleaning it but be careful not to break the hot surface igniter. A bad ground wire on the burner manifold / gas valve or low gas pressure can give the same symptom.