Faild Smog. High "NO" Nitrogen Oxide levels are high

[E30Savage]

So my 325i E30 failed the smog test today. On the print out it says my Nitrogen Oxide "NO" levels are high. Everything else was good. Does anyone know what might cause that and how I can fix it?

[CarsSuck]

your engine may be running lean or you're catalytic converter has aged beyond it's usefulness.

[paperplane94]

Vac leaks, Vac leaks, Vac leaks...

Have a shop run a smoke test, you are too lean.

[jlevie]

+1

Either the engine is running lean or the catalytic converter is bad. A smoke test should be the first step. Then check rail fuel pressure.

[E30Savage]

The catalytic converter is less than year old, so i doubt that's it. But I will definitely looking into those vacuum leaks. Thanks for the quick responses.