Not true, A lot of emission Related component can effect nox,but the main 3 are a Cat, 02 Sensor and EGR You cannot say EGR is the main cause of a high NOX reading. Im a Emission Test Inspector shuffle and Work at a Accredited Repair Facility, We fix at least 3 cars a week, that fail emission, From personal experience a Failing cat is the most commonly problem with NOX. Last week we had a 2005 Toyota corolla that failed with only 120k on it, The cat and EGR system were good, it was a failing O2 Sensor...Just shows you EVERY CAR is very different and you cant base your results on the mr2....

Last edited by Deep Mann; November 19, 2009 06:20 pm UTC.
1998 Tsi Awd 10.6@134