Furnace throwing a 31 fault intermittently I went down thinking that was high limit fault and began adjusting temperature rise. Admitted mistake to homeowner and verified the code is for the high pressure switch opening. Cannot verify if intake and exhaust are 100% free of obstructions because the flush mount termination kit is glued onto the exhaust pipe (cover should not be glued to anything, it is held on by 4 screws). Homeowner is going to reach out to the builder to see if they will replace the termination cover. Furnace ran for the entire time I was there without throwing a fault code. It cycled back on and off normally with calls for heat. If the intake and exhaust are clear, next step is a parts warranty pressure switch. Verified inducer is pulling 0.6"wc while heating, switch is rated for .35" Did not see any major variations in the pressure, either. Verified inducer capacitor is measuring the rated 5mfd Looked up a Carrier service bulletin TIC2017-0001 regarding nuisance