Patman

I've been getting a check engine light come and go on my C6 for the past few months so I finally got around to buying my own code reader and it shows a P0420 code (catalyst system efficiency below threshold bank 1) and I was wondering if anyone else here has run into this and what did you do to solve it? It seems awfully early for a catalytic convertor to go bad, with only 62,000 miles on it and considering it just passed an emissions test when I bought the car in April.

eboggs_jkvl

Inspect for the following conditions:


Inspect the three-way catalytic converter for damage (dents, severe discoloration caused by excessive temperature, holes, etc.).
Ensure that the internal three-way catalytic converter rattle caused by damaged catalyst is not present.
Inspect the exhaust system for leaks, damage, or loose or missing hardware (area from converter to HO2S #2 primarily).
Ensure that the HO2S #1 and the HO2S #2 are secure and that the pigtails and wiring are not damaged or contacting the exhaust.


Elmer

TJay74

That is a sign the cat is going bad on the drivers side.

VETTE_69

Replace driver side cats... Change mine with magnaflow direct fit cats then clear DTC code pass emission no problem last monday!

Hope that helps!!!

MikeyTX

Comes from buying cheap cat food at wally world ........................... ...............

RocketDawg

Sometimes they fail, and it could be because they weren't very good to begin with. They get bad batches of parts too.

We had a 2006 Cadillac RSX and had to replace both catalytic converters (at different times). No check light, but the cats started rattling, like marbles in a can. One was at about 40,000 miles and the other at about 60,000. So they do fail before they should.

Both of ours were covered under warranty, and yours probably will be too. I think emission-related repairs are covered for something like 8 years/100,000 miles, but check your warranty manual.

melgies

Isnt there a program you can buy to shut off a faulty check engine light? As I know there is nothing wrong with my cats??

skar

I have same code plus po430 I have kooks headers and cats .
and now have a rough idle and if I hold it at 2,000 rpm still rough .
liginfelter tune .

Patman

I’m not sure why my 6 year old thread was resurrected but I don’t even have my C6 anymore (now have a C7) and I did end up having to replace one of the cats on the C6 back then.

Bruze

There seems to be a lot of posters lately, who've been members for years yet have only averaged 3/4 of a post per year, who revive ancient threads.

Not sure why.

C5forGreg

Probably, but they are usually sold as "for track use only" because they wouldn't be legal particularly in any state that checks emissions annually. The issue may not be a CAT, however, sometimes it can be an O2 sensor that is acting up. I bought a used Toyota once, for my daughter. Had a 5 hour drive home after picking it up and the CEL came on about half way. I stopped to check the code and it was P0420. Cleared the code and it came back the next day. After doing some research online, I decided to try the sensor first since it was a cheaper part and easy enough to change. Never got the code again.

Does seem to be a lot of threads coming back from the dead lately.

FactoryZ51

me neither