My CEL came on probably a couple months ago out of the blue. I got it read and it showed that it was throwing a P0420. I then unplugged my battery terminals to reset my ecu. Its been a couple months already and the light still hasn't come on yet. Do you guys think its a false code?

 

P0420 Catalyst System Efficiency Below Threshold...
no idea. catalitic converter? too cold? idk. delete cat and disable 2nd o2
its nothign to worry about

 

You think ill pass smog then? lol... The light never came back on

 

That engine code means your engine is ready to party. Blaze up your hitter and put it in the intake.

Hahaha mods I couldn't help it.

You could do what rick said (delete cat and 2nd o2), but if my memory serves me correctly, you will need a resistor in the second o2 circuit so the cpu thinks the 02 is still there. Or you could go the legal route and just have a new cat welded in, maybe a high flow magnaflow. I got that on my civic and it pops and makes growly notes all the time. Pretty awesome.

 

if you have to be smogged i beleive they see past codes the ecu stores even if they arent there now. thats the case with bmw and newer cars. not sure about obd2a.
you should be fine. if they ask tell them it came and came off. shouldnt be an issue