Hey guys so I got a check engine light on my C6 and when I scanned it it came up with code P0420. The code says the catalyst system is below threshold on bank 1. On my OBD reader which is a cheaper one it says one is stored and one is pending not sure if that has anything to do with one or both 02 sensors. but the car only has 50k miles so I doubt it’s the cats. It also has an NPP exhaust with the fuse pulled not sure if that matters or not. I’ve driven the car a good amount and haven’t had any problems until now. I read that it could most likely be an 02 sensor I’m wonder what my first course of action would be in terms of fixing that and is the car okay to drive while showing that code. The car doesn’t feel any different in terms of driving and if it is different It’s a very small amount, so what should I do first to rectify this? Thanks ahead of time for the advice.

 

Pretty easy to find good resources to help you diagnose the code:

https://www.google.com/amp/s/www.car...ld-bank-1/amp/

 

1) If any other DTCs are set perform those diagnostics first.

2) Inspect for the following conditions, which may cause a catalytic converter to degrade:
• An engine misfire

• High engine oil or high coolant consumption

• Retarded spark timing

• A weak or poor spark

• A lean fuel mixture

• A rich fuel mixture

• A damaged oxygen sensor or wiring harness

• The catalyst test may abort if the vehicle falls outside the conditions for running the DTC.

• A catalyst may be temporarily degraded if a fuel with high sulfur content has been used. Drive the vehicle at highway speeds for 10 minutes and retest the converter.

3) Operate the vehicle within the Conditions for Running the DTC.
⇒ If the DTC fails this key cycle, continue with this procedure.

4) Inspect the catalytic converter for the following conditions:
• Dents

• A severe discoloration caused by excessive temperatures

• Road damage

• An internal rattle caused by damaged catalyst substrate

• Restrictions

⇒ If a condition is found, replace the catalytic converter.

5) Inspect the exhaust system for the following conditions:
• Leaks

• Physical damage

• Loose or missing hardware

• Properly torqued HO2S

• Restrictions

⇒ If a condition is found, repair the exhaust system.

6) Inspect the post catalyst HO2S for the following conditions:
• A grounded wiring harness

• Damage

⇒ If a condition is found, replace the post catalyst HO2S.

⇒ If no physical condition is detected, replace the catalytic converter.

 

I'm assuming no mods like headers, etc and has any engine changes been made recently? I am DIY, not a professional ASE mechanic.
Keeping it simple = I'd presume it's a precursor to the cat going bad. If/when it does you will see a smoke/material plume from the exhaust.
NPP fuse will not be the issue.

It could be anything above, but you're not getting any other misfire, ect codes and you stated no loss of power, etc. so I wouldn't lean toward something like a harness melted wire, broken wire at the connector, bank 1 injector stuck open/closed (too much/little fuel), etc. Rule out vacuum leak since it's not both banks.
O2s/Catz are fun

If comfortable checking voltages be careful to not jumper/ground the wrong pin(s) or the magic smoke will be released from the ECM. Use test light, or meter only.
Fuse 6 in the under hood box provides the 12V on the solid Pink wiring @ Pin D on all of the HO2s.

Stored, is code that has been set. Pending, for example, is a condition that may take 2 instances of it to set a MIL (check engine light)

They just go bad sometimes regardless of mileage/usage/etc. Defo have it thoroughly checked before committing to such a large expense.

 

Here is a link to look up codes:

https://www.autocodes.com/

 

Not sure what year your car is but there was a factory recall on the C-6 which replaced the exhaust system and cats at no cost from the headers back to the NPP. Mine is a 2009.

 

interesting? Nice one George!

 

I've driven my Z06 for 12 years, first only owner.
At 52K threw a P0420 and it was a bad cat *&* O2 sensor.
Don't assume it couldn't be both, both do fail w/ nothing to do w/ NPP et al.
Whether dealer or indy shop, those 2 components need to be replaced or code will never clear.

FWIW been golden since CC & O2 were replaced on mine. YMMV

 

 

It’s a 2008 but I’m not sure how to go about going in for a recall on a secondhand vehicle who would I contact?

 

K thanks