I have a York Multiposition GF8 furnace GF8125D20MU11 which has been running for about 6 weeks in my attic (boy was that fun getting it up there!).
Following a power outage the furnace stopped working.
The diagnostic LED flashes 7 times which indicates:
"7 FLASH: This fault code indicates that the flame could not
be established. This no-light condition occurred 3 times (2
retries) during the call for heat before locking out. This may
be caused by low gas pressure, faulty gas valve, faulty hot
surface ignitor or burner problem."
When I power the furnace off and then on, the vent blower starts, the hot surface ignitor glows bright orange, the gas ignites for a few seconds and then stops. As you all know, this occurs 3 times before the system locks out and the LED comes on.
From reading previous postings I have removed, cleaned and reinstalled the Sensor Rod with emory cloth and fine sandpaper. I have checked the connections on the yellow wire for the Sensor Rod back to the IC board and there are no disturbances. Nothing else about the IC board seems out of place either. I have also tested the main blower assembly and it still circulates air through the system perfectly.
Any further advice would be greatly appreciated!