My Truck failed its first smog test because of High Oxides of Nitrogen (NOx). The California State Max reading is 501 and the average is listed at 149 at 15 mph. My truck reached 780. So I replaced the EGR Valve. On the second test it failed again, this time the reading was 773 at 15 mph. I also noticed that the NOx emissions at 25 mph had been reduced by 69 points. I drove the truck for 10 miles before taking it in for the second test. Everything else passed inspection. 2 years ago I replaced the Oxygen Senor, which passed again. This truck has had only one owner, me. I do not drive it much, because I have another vehicle and those are the original miles. I do my own repairs. So my question is, "what else could be causing these high emissions." Since my last smog check I have only put 1400 miles on the truck. If that makes a difference. Thanks.
Oct 27, 2008 at 6:11 PM
