We recommend visiting the page below to learn more about what could have caused your 2002 Ford Escort to produce and fail because of high NO. Typically high NOx is cause due to defective a dirty or defective EGR valve. For high NO failures where the EGR system is inspected and no faults found it is recommend to check for vacuum leaks and problems which could cause a lean air/fuel ratio.
What causes high NOx?
