Failed smog 722 "NO (ppm)

[1SicDsm]

Hey guys just a quick smog question from Cali, i failed smog my car has 60k original, so I'm hoping it's nohing big, ib passed everything with flying colors except at 15mph it had 722 NO (ppm) I have no idea what that is, my friend said it was cause I did t warm it up till I was hot any suggestions??

 

[SlowSpyder]

I would suggest driving it like you stole it for 10-15 min before you get the smog. The cat needs to be hot in order work properly and cut the emissions down.

 

[alex1090]

Running a car through emissions testing while cold will produce low NOx readings. High Nox readings are cause by higher than normal temps, weather that be coolant temps or exhaust temps, Clogged EGR passages will cause this, as well as the EGR valve not working at all. Usually when you have a bad Cat, readings will be high across the board rather than just one reading

 

[4g63GalantGSX]

Clogged EGR passages will cause this, as well as the EGR valve not working at all. Usually when you have a bad Cat, readings will be high across the board rather than just one reading

Thats what it sounds like, the EGR Valve, apply a vacuum to it while the car is running, if the idle changes the valve is working, if no change, replace the valve.