The CO failed by quite a bit, I think 1.2 was passing, and I was 4.5 or so. I don't understand any of that. I've put in a brand new K&N, and run SeaFoam through a tank, and "Guaranteed" to Pass through another tank. While that combination lowered it about 1 point, I'm still 3x's too high.60wag said:What did it fail for - CO, HC, NOx? What have you done to it since the other tests?