Couple check engine codes - Chevy Cobalt SS Forum : Chevrolet Cobalt SS Forums
LinkBack Thread Tools Display Modes
post #1 of 2 (permalink) Old 02-19-2011, 04:37 PM Thread Starter
Junior Member
Join Date: Feb 2011
Posts: 5
Couple check engine codes

Okay, so i've had a check engine light on for a while, and finally got it scanned.

The codes that came back were

P0420 - catalyst control system below threshold (bank 1).

I have a 2005 cobalt, 2.2 litre. What are the chances it's actually the catalytic convertor, and not the downstream o2 sensor? The o2 sensor is $50 for a delphi one, and the convertor is $400. I'm debating on spending the $50 for the o2 sensor just to see if that's the problem, but if it's just gonna be another $50 wasted (I was told by autozone that it was the upstream o2 sensor throwing that code), than I might as well just spend the $400 and be done.

My state doesnt require emissions, so I don't qualify for the 8yr 800000 mile federal replacement warranty

Also, another code that was thrown, I can't remember the number, but it described it as this:

Evaporative Emission Control System Leak Detected (Large) - Occassionally, when driving, the car will ding and the 'check gas cap' light will come on, even though the cap is down as tight as it will go. Would a 'large' be classified as a faulty gas cap gasket, or is it something else somewhere.
ex0r is offline  
Sponsored Links
post #2 of 2 (permalink) Old 02-20-2011, 05:19 PM
Contributing User
Join Date: Aug 2008
Posts: 401
Personally I would, if you have the money to spend $400 right away do that. If you don't take the chance with the $50 one and see if that works. If yes, then you saved $350. If not you only spent $50 extra and you can wait awhile while you get the money. But $350>$50.

Just my advise. For what its worth.
SupremeSlacker27 is offline  
Sponsored Links

Quick Reply

Register Now

In order to be able to post messages on the Chevy Cobalt SS Forum : Chevrolet Cobalt SS Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Similar Threads
Thread Thread Starter Forum Replies Last Post
Check engine light BeltDriven Problems/Dealer Service 7 05-21-2006 09:25 PM
Check engine [email protected] Problems/Dealer Service 7 12-05-2005 04:03 PM
Check Engine Light labelkills98 Problems/Dealer Service 10 07-08-2005 09:03 PM
Check Engine Light Again BizoCG General Discussion 16 06-29-2005 07:05 AM
Another Check Engine Light... dervin3 General Discussion 10 06-02-2005 10:02 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome