Quote Originally Posted by bellavite1 View Post
Managed to find the error code, pointing to the thermostat.
That's.... unusual. Like I've rarely seen a board in a home furnace that can diagnose a tstat issue. And the ones I've seen than can, the HVAC system is worth more than many vehicles are.

What brand of furnace? If it's a Coleman 8 flashes does not mean a thermostat issue. It just means its cycles too many times and locked out

Goodman 8 flashes means no ignition detected. Could be ignitor or flame sensor


After re reading a couple of times. Your description of the symptoms seems to be the flame sensor.