Not sure if I need to post in this section of the forum but here it goes.

Hi,

My son drives an 05' Civic (non-VTEC). Last month his radiator failed etc and he ran the car on the freeway too long and burnt the motor (no oil and no water). Not sure how long he ran the car for w/out water/oil but it was enough to do this much damage. A compression test confirmed a failed motor (it actually smelled like burnt oil under the hood plus there were some slightly melted plastic parts; timing cover etc).

Fast forward and we found a replacement motor (1.7 non-VTEC) and the mechanic installed along with a new radiator, water pump, timing belt etc. The cars runs really nice now EXCEPT that a couple of days after driving maybe 50 miles the "check engine light" came on with code P0420. I proceeded to drive the car and two day later, the "check engine light" went away and has not returned in about 5 days or so (100-200 miles driving; maybe).
I went to get a smog check and the smog tech stated that the car has stored code P0420 and thus fails the smog inspection. I'm confused as the "check engine light" is off and has been off.

What am I missing and what can I do?

Thanks in advance.

 

have you "reset" the computer and then run it a few hundred miles then have the smog check done providing the p-0420 check light does not come back on. AutoZone may be able to reset this or your mechanic if they have the tool to reset the computer.

 

I have not. Should I reset the computer even though there is no "Check Engine" light on? It has not returned since it went away 4-5 days ago.

 

The ECU will have stored this P0420 diagnostic trouble code.
That is what caused the failure in your area.
Clearing the codes is as easy as disconnecting the battery for a minute or so.
Then you have to drive the vehicle for about fifty miles or so
This lets the readiness monitors do their tests and set up

Here is hoping the code does not come back again.

 

I disconnected the battery and drove for 50 miles and the code came back. Question, do the catalytic converters that are not carb compliant pass the sniffer in CA? I know they can't be sold in CA but I have family that lives outside of CA and can ship to me. I assume the only difference is the CA cat has the carb stamp. Aside from that, will a non-CA cat pass the smog test?

 

In NY, the cat is registered with the state.
They will inspect it and it will fail.
They check it every time they inspect the car.

Don't know about CA.
But, suspect they will do the same.

 

If you have a code and reset it and take it in for smog the smog person will tell you to drive it a bit more and come back. If the light goes off. The computer will pick it up. If you install a non-Ca cat. It may it may not pass the smog.