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I think you’ll find it’s more likely to be an igniter issue (gap, bad unit, etc).  The flame sensor only keeps the burner burning after it’s started.  It does not prevent startup. 

Your original post stated “It worked fine prior to nozzle and after.”  Is that correct?  Meaning it was working correctly after you replaced to nozzle, but now it’s not (no ignition)?

Yes.  Had too much white smoke so I replaced nozzle.  Smoke went away aside from a little residual that was probably in the exhaust pipe that needed to burn off, but it was working fine.  Went on a trip a few weeks later and mid trip I noticed I had flipped on diesel one day as we still needed some A/C during the day and it would not fire.

Tried to be super careful when replacing nozzle to not move points and I did clean the photo eye.