So, I failed the dyno smog test because of a high nox reading. In the 15 mph test I measured 706 and the max was 704. ughhh. The nox at 25mph was a little high but within the limits, the HC and CO were below average. Anyone know what could be wrong or how I could get it to pass?

 

Got any mods?

 

nope

 

your cat is toast.

i've got the same problem,
with my 92 honda cx,
all stock, but it has 150k on it.

I failed twice,
and after the first time, I went and tried as many little "tweaks" as I could to bring downthe emissions,
none of it worked.

people "in the know" told me its definetely my cat.
so i'd say, make a post on here somewhere asking to borrow someones stock exhaust, hopefully with low miles on it, and try it with that,

by the way,
my score was well below on HC and CO, but over on NOx also