P0420 code?

[volcombug]

What does this one mean? I saw what it says on the code list thing but I still not sure what to think. This code popped up today on my way to work.

[SMG]

That's a secondary O2 sensor code. You either have a bad post-cat O2 or a bad cat.

Good luck!

SMG

[99beetlefl]

Actually a 420 code is a cat effiency below threshold code

[SMG]

Yes, but it's the 02 sensor throwing the code. Meaning that the cat is worn out, or there's something wrong with the 02 sensor and it's getting bad readings.

[volcombug]

Okay so the code P0420 popped up again today. How should I go about getting this thing fixed? Should I replace the O2 sensor or should I just do that Cat? If so how much do they run and what's the best place to get the stuff? Can someone let me know how I should go about this all. I hate it when my car has something wrong. It just makes it it less as fun to drive when you have to drive around looking at the check light. Thanks!
I was looking around on some other topics and now I need to know if it's the rear or the front o2 I need to replace. I found the front for $150 and the rear for like $89. If all else fails I could take it to VW. They said if it falls under 7 years or 70,000 they will cover it if its emissions warranty. It will still cost me $100 something to have them look at it. Let me know.
Volcombug

[barrabiuri]

Hello volcombug !

If your problem isnt the sensors its the cat... I had the same problem, and someone here on the org directed me to a VW specialist and he diagnosd my car for free and even printed out a sheet for me in case VW tried to fool me or deny service...I took it to VW, my car has currently 82,000 and it was still covered under warranty..i didnt have to pay a thing !

When my cat went bad, I was at a gas station everyday! considering i dont drive the car for longer than a full hour everyday...tiny bis here and there..anyway..also, I could smell some strong fumes and my car made a rattling noise...

so when you go to the dealer, LET them know that you know itts covered untill 100,000 miles

good luck

[volcombug]

Thanks barrabiuri I will let you know. I am just waiting for the light to come back on then I am going to take it to VW. It all should be under warranty.

[barrabiuri]

=]

good luck

[barrabiuri]

I heard that when you get an oil change, if the oil is above the line, that can also cause your cat. to go bad. And my light did show up a couple of hours after I got an oil change...

[SMG]

It's totally a coincidence. A cat can't go bad from being run for a few hours with a bit too much oil. I've overfilled mine a bit before and it never hurt anything.

[barrabiuri]

Originally Posted by SMG

It's totally a coincidence. A cat can't go bad from being run for a few hours with a bit too much oil. I've overfilled mine a bit before and it never hurt anything.

o0o i see..well i really dont know, i just read it somewhere in the org

thanks!

[volcombug]

Well all I took it in to VW at about 8AM today and I didn't get out of the place till 3:30PM. They ended up changing of the cat so I hope that's what was bring up the code. Oh and they didn't charge me anything. I did get a ton of FREE soda cause I was just waiting around. If anyone needs a good VW dealer to go to Ontario VW is the place to go!

[dizzy]

VW sent me an official notice of warranty extension for replacement of the catalytic converter for up to 10 years or 100,000 miles.

I'm taking mine in next week to have it changed, I had the P0420 ODBII code flagged. They will replace the converter before any sensors or it will be on their dime.

[JLasvegas]

Got this code today, cleared it and drove back home, it didnt pop back up but who knows how long that will last, has anyone ever cleared a code and had it not reshow?
my car passed emmissions no problem last week so it seems odd

[Smileybug]

How long did you drive it after you cleared the code? It will take the car a good bit of miles before the code will reshow (if the problem wasn't fixed). About 50 miles or so. There is this period of time so that if you have a code thrown, you can't just clear it and go get it inspected. It all has to reset itself after a certain amount of driving first.

[JLasvegas]

I have only put 41 miles on it since I bought it. between the starter screech and this code im already regretting the purchase.

[JLasvegas]

would you suggest replacing the rear 02 sensor first before looking into the cat?

[HudsonValleyVDub]

50 miles to re-show a code? No idea where that came from but if you clear a code and don't fix the problem, the CEL will come right back on. 50 miles for the light to shut OFF after fixing a problem maybe, not to come back on. Been there done that.

[Smileybug]

I know for a fact it takes a bit of driving for the light to come back on. I had a completely dead O2 sensor that was throwing a code. I knew it was dead but didn't want my CEL on all the time so I cleared it. Didnt come back on right away but I think after 2 days of driving to work and back it would. Which was about 50 miles. I cleared it one or 2 more times and it took the same amount of time to come back.

The driving allows the car to reset the readiness codes. This means if you clear the code and drive right to an inspection station, you won't pass, as it shows the readiness codes not being set and therefore you could have bad components.

[HudsonValleyVDub]

Originally Posted by Smileybug

I know for a fact it takes a bit of driving for the light to come back on. I had a completely dead O2 sensor that was throwing a code. I knew it was dead but didn't want my CEL on all the time so I cleared it. Didnt come back on right away but I think after 2 days of driving to work and back it would. Which was about 50 miles. I cleared it one or 2 more times and it took the same amount of time to come back.

The driving allows the car to reset the readiness codes. This means if you clear the code and drive right to an inspection station, you won't pass, as it shows the readiness codes not being set and therefore you could have bad components.

I delete the message I just wrote because I'm apparently wrong! I just disconnected the connection to my MAF and....nothing...no light, no drivability issues at all. So my apologies to you Smileybug. Unlike all the Nissans I've driven through the years, it seems it DOES take time for the CEL to come on!