Recently went to go do state emission test and failed twice, once because of p0171 code with high NOx to which the code is now fixed because I found the air leak leading to a hose connected to EGR vacuum modulator. Thinking I would pass second test I did not. EGR valve (which is working by completing multiple test on it) and its passage way have been cleaned, what else is the reason to a High NOx?
have the same problem?
Wednesday, March 18th, 2015 AT 7:51 PM