Hi Everyone - My 1993 Accord Wagon just failed smog today. It sailed through with flying colors on all measurements but the NO at 15MPH.

At 15MPH the NO was 760 while at 25MPH it was at 23.

Any thoughts on what to do first? The smog tester suggested a new oxygen sensor, but reading online I see the EGR valve should be replaced or cleaned.

Thank you for your thoughts!

 

Post all gas readouts.
If you are in Calif, post the 5 gas test results.
Just because one gas failed does not mean that was the sole issue. There may be other problems. Excessively low numbers are also not good.
Post CO, O2, CO2, NOx, HC readouts.

 

Post a pic of the results sheet. More than likely you will need to remove the intake manifold and clean out the egr ports. I had to do this on my 90 cb7 coupe. There are little plugs in the manifold that I ended up drilling and tapping a hole for an m6 bolt and pulled them out. The egr passages were completely plugged with carbon. If you don't have a way to remove the plugs and ensure they seal when you replace them there really isn't a good way to do it properly that I know of. I just didn't want to do it again.