Well i just left a local bar, and on the way home i noticed that the CEL light was on, so i swing into o'rileys and they check the code for me, it said P0420...anyone know what this means?

 

Bad O2 sensor maybe?

http://www.obd-codes.com/p0420

 

im hoping that is all it is...obd-codes also said it could be a bad cat wtf???

 

It can happen... but if you're lucky, just an O2 sensor. The question is... which one?

 

Yeah, that does mean a bad cat... so it is either the sensor or cat itself although hopefully not.. Depending on where you live, you could just weld pipe in its place and CEL fix for your sensor if you want to go cheap

 

That is only for the 2nd cat tho

 

Bank 1 means first cat... the one in the mani. More than likely its the sensor, thats what i would start with anyway(its cheaper). I know if someone came into my shop thats what i would suggest to them! GL though

 

It's like 160 from auto parts stores.

 

yeah, a P0420 is Catalyst Efficiency Below Threshold. either your cat is going/gone bad for your post cat 02 sensor has failed.

 

Do you have an aftermarket header? Surprised no one asked that yet...

 

Bank 1 means engine bank one. Being an inline engine, they are always bank 1. There is bank1 sensor 1 (primary o2.. used to monitor AFR) and bank 1 sensor 2 (used only to monitor if the cat in the manifold, the first cat, is doing its job). An aftermarket header without a CEL fix will cause this code since the first CAT is removed as well.

And swapping parts is a poor way to fix an issue and can lead to wasting money. Asking the question I asked above, then actually finding the proper voltage to the o2 and measuring its actual voltages under operation is a better solution since you will many times rule out the o2 or pinpoint the issue before. If the cat is bad (assuming it is still there) then buying an o2 sensor is just money down the drain.

 

If you have a header on your car and this is the code being thrown, put a spark plug anti-fouler on the secondary O2 sensor and call it a day.