Thread: Need a little help passing my inspection

Tweet

Originally Posted by RAYJAY

OK I'm new here but if your running a cat on the car /truck (more info on what your running would help ) do you have o2 sensors on the motor also ?

if you do and there over 75,000 miles they will cause a load of problems

jeff

He is failing on NOx, 02 sensors will not cause a NOx failure,unless it's very very lean but if it was it would usually cause an HC failure also. 4 things will cause a NOx failure,
"in order of most common"
1....EGR system
2.... Catalytic converter.. usually will fail NOx along with HC.
3...Advanced ignition timing..
4.... overheating engine...