At what OHMS reading does the gas furnace ignitor need to be replaced? It is a White Rogers furnace.

The main issue with HSI's ( hot surface ignitors) is that you have an ohm reading which is showing continuity through that heating element. Set your meter for continuity and check to see if your meter beeps and / or shows a complete circuit through the two wires of the HSI...

If it is a hot surface igniter and has no continuity through it then it is bad or you can see a crack in the igniter, it will show up as a white line across the surface, Mike