I got an 01' civic ex coupe, im stationed here in cali so of course we got emissions here, but the other day when i took it in to get smogged it failed due to "NO" and "CO", the guy told me to do a tune up and get it re tested. I did the tune up and took it back, only to find out the points when UP!!!! HEEELLLLPPPPP. I took to get diagnosed and the place said that nothing was wrong with it, but when they put the thing in the exhaust it came back running lean. THATS IT... so i took and another place, they have had the car for three days now and still cant figure this out, there is NO check engine light on, the car runs great with no problems, no poor gas mileage or anything. the guy called me today and said they want to just start replacing stuff starting with the o2sensor (post cat). I told them no, i dont want to just start REPLACING stuff if you're not sure its going to fix it... I need help, as we all know, military pay is not much, i got a family which makes it even less... I can replace the o2 sensor myself if it actually needs it, but i need to know if the ecm needs to be reset or not, and if so how do i do it?!?! ALL AND ANY HELP IS WELL APPRECIATED thank you!!!

 

Excessive CO is caused by a lack of an oxidizer. Not lean, rich. Nox is caused by oxidation of Nitrogen. Excessive heat causes that. I would suspect EGR issue.

 

so with that said would you suspect that i should replace the EGR valve?!? both places that tried to diagnose the issue said that they looked at the egr system, along with the ecm, converter, fuel management, everything they said, the first place did say it way lean, but when i took the notes to the second shop they said no, its rich!!! so should i just turn away from the o2 sensor and go to the egr valve?!? thanks for the reply!

 

The car should die if the valve is opened at idle. If it doesnt I'd say there is a problem.

 

well the o2 sensor was replaced today... the points are now way lower than before but still above the max... so tomorrow morning they are supposed to be checking the egr system as if they havent done it already... the car doesnt die at all, it runs great!!! allways has so im lost