Confused code P0420

[dangerranger2000]

I am new here, although as time allows I will be on here alot. I have searched the forums a little bit for this problem, but still am not sure how to progress. A few days ago I got a code that comes on everynow and again saying one of the o2 senors is bad, since they were all original I decided to replace them all with Bosch, now I am getting a P0420. How can I test the sensors or the cats? Any help or links to help will be appreciated.

 

[PhantomOfTheBumpside]

420, any way you look at it, means you're toasted.

Or your converter is on it's way to being toasted..

You could try replacing the rear sensor again... but, if you have been skipping or stretching out maintenance, and even given the age of your cat, it's a sure bet you are actually clogging up.

You will start to notice a loss of power or lag as the converter continues to clog.

If/when you replace, tune it up proper immediately. If your engine has internal problems that are causing oil burning or coolant loss, you'll probably plug up a new converter pretty quick too...

 

[dangerranger2000]

Thanks for the reply Phantom, I have been thinking the same way. I have done some digging and think since the downstream o2 was black it means the truck is running rich, so I am going to check into that. As soon as I can I have plans to rebuild a 3.0 with more power to drop in my truck,; when I do that I will be replacing the whole exhaust anyway. Hopefully my truck lasts till then.

 

[adsm08]

Honestly, the cat is probably bad. Odds are that the old catalyst monitor was old and lazy and didn't show the switching fast enough to set the code.

 

[dangerranger2000]

adsm08 I am having to admit to myself that I need new ones. I have no drivability problems so far, so they will have to wait till the money rolls in. Thanks for the input.

 

[dangerranger2000]

Here's an update. I tried some cat cleaner, didn't work. My truck is a flex fuel vehicle, so I filled up with E85 because it burns hotter and I figured that clean everthing out. I am getting poorer gas this tank, but after some smoking the check engine light went out.