Customer has no heat. Upon arrival found control board showing error 228 failure at pressures switches. After further inspection found high fire pressure switch in the closed position while furnace not running. This indicates failure at internal pressure switch contacts. Was able to get switch to open. Performed draft test with manometer and ensured no obstruction in venting. All hoses and wiring is proper as well. Pressure switch needs replacing. Currently heat is on and working properly. But this can reoccur again. Customer is having an open house tomorrow as she is selling home.