Ford Repair: 1999 Ford Contour se 2.5 L V-6, ford contour, smog test

Question
I took  my car for a smog test and it failed the emissions test, high NOX.  Can changing the spark plugs, spark plug wires and air filter fix that?

Answer
Before you throw parts at the car, retrieve the trouble codes stored. The check engine light is on, right? Let me know what codes are present, and we can go from there. Your catalytic converters convert the NOX into water, so if the NOX is too high, you probably have a faulty sensor. The trouble codes should tell which sensor is malfunctioning.