We have a new OTC 3209 scanner. Has anyone ever used one to see what was happening when the above code goes off? We know thermostat is the most obvious but we are getting good heat. The code doesn't go off for a week after we reset. Last time we reset we had a few days of extremely cold temps (-2) and it was good but then went off a week later again when temps were actually in the 30's. Before digging into the thermostat wanted to verify what is going on? Possibly an intake air sensor or ECT or something else in the wiring. Seems like issue started after removing engine cover to inspect plugs?