Decisions Decisions: Help with a P0420?????

[Jbot]

Hey all, i know there are multiple threads on this but if anyone could give me specific advice id be grateful.

My CEL has been coming on for the past month and is giving me the P0420 code, emissions. From what i understand its either the cat(s) or the O2 sensor, but there's no way to find out which. Im a college student and obviously not so flush and dont have many tools or space in my apartment parking lot. So as far as i can tell these are my options:

1) replace O2 and hope thats the problem, but if the cat is bad itll just burn out the new sensor...
2) ignore it until i have to (i have 1 year til smog)
3) replace cat

I know it may seem a simple problem to have but im just confused since this would be my first big expense on the runner. Any advice or opinions would be awesome.

Thanks
-Jay

 

[Diezel]

I know it may seem a simple problem to have but im just confused since this would be my first big expense on the runner. Any advice or opinions would be awesome.

Thanks
-Jay

Well, there is a chance, the o2 sensors are "slow". Which can cause a CEL and stored code of P0420. The only way to know for certain really, is to have a scan-tool where you can look at the switching times of the o2 sensors. You could do it with a multimeter, but I prefer the non-invasive method of a scan-tool.

The switching times of the sensors, can help you to confirm if the Catalyst really is the root issue. Be warned though, usually the P0420 code, has a root cause IF the catalyst is going bad. The source of which should be discovered and repaired before replacing the Catalyst.

 

[Road Bull]

Had the same P0420 code for my 2002 4runner. I started by buying a can of Mass Airflow Sensor cleaner to give the that a go. That seemed to fix it for a week or two. Then the CEL and VSC / VSC TRACK CTRL came back. I ordered a $53.00 O2 sensor from amazon. Picked up a 22mm opened ended wrench along with some PB Blaster lubricant. I swapped the old for new sensor, and in ~60 miles, CEL was off and has been off for a few weeks.

That's about as cheap a fix as you're going to find. Good luck.