Have been chasing a Code 1 on my Civic for many months and it is stopping me from registering the car now. I have measured the O2 sensor voltage and it shows right where it should be at about .45v when idling and at 2,500 rpm so I don't think the O2 sensor is the problem (plus the O2 sensor is new). I just realized that the CEL does not go off when the car is just idling so I am wondering if this has to do with the issue I have had in the past with the CEL going off when the car is driving at least 20 mph and air is flowing through the engine, perhaps due to a misreading on the airflow somewhere on the engine? Anyone have this happen before?