Usually when the ID is getting no power on a 90% and the fault code shows nothing unusual with a call for heat, the problem will be in the thermostat circuit, the board or condensate pump switches.
When you say you bypassed the sensor, are you saying that you bypassed the thermostat? I would try jumpering the thermostat connections on the furnace board at R & W when the thermostat is turned down.
Is the transformer supplying 24 to the thermostat?
Does your unit have a condensate pump?
I am assuming that the two steady lights are saying that everything is OK but you should have a legend on one of your furnace doors that will confirm that.