I just installed a new CAT due to mine going bad. I have a check engin light on now. I'm guessing I need a new 02 sensor. Which one do I need? I know one is like $50 and the other is over $100. Or should i get both? Does anyone have a problem getting it from places like ebay or advance auto parts compare to the dealership or gmdirectparts?
I rather not pay $90. Getting autozone to read it will only show code po420
Rich Grayo Jr. wrote:dont guess. get the code read.
would be a good idea to do this, but if you think 100% its the O2 sensors, just crawl under there and check to make sure they are all plugged in or something. otherwise just replace them.
12.33 @ 111.67 mph [Oct 2009]
Dyno'd on 08/02/09 - Mustang Dyno:
327.6 WHP 333.6 WTQ [10.1 AFR]
LINK
Your computer thinks the difference in temperature between your upstream and downstream EGT (o2) sensors is not enough.
Or your new cat acts different from the old one.
I haven't run into this yet, so i don't know what else to tell ya.
ZZZZZZZ
0420 is generally for your post cat sensor. its the expensive one, so make sure its installed and plugged in correctly. you should NEVER have to pay to get a code read, as getting advance/autozone to read it for you will yield the same result as a shop.
JBO Stickers! Get yours today!
The after installing my new CAT from ebay the 0420 code showed up. I would had thought it was an 02 sensor. The shop diagnostic as the CAT was defective. So I had it taken off and had them install another new from that they had. Still the p0420 code shows up pointing to the converter. They replaced both 02 sensors and still the p0420 code is pointing to the converter. What else could this be?
Was the codes cleared after the new parts were installed?
FU Tuning
Yes it was! After each time it's clear I drive it for like 60 miles before it comes back on again
What kind of cat exactly did you replace it with. Some people hav e had issues with certain high flow cats throwing a code.
FU Tuning
First of all the O2 sensors does not read the difference in exhaust temperature ( Read a book) They read the difference in gases in the exhaust the front one reads the how the engine is running if it it rich or lean and the rear one telling the computer how the cat is performing by comparing it to the first one. It is on a scall between 0 volts to 1 volt and the perfect fuel mixture is at .5 volts. So the only way to know what O2 is to get the code reader and it will tell you and the shop will be able to tell u front or back.
This is the original one I bought from ebay
CAT
When they said that was pulling a code because it was defected I told them to go ahead and replace it with a good one. I don't remember the brand but I know it wasn't the same as the one from ebay.
Sleep the shop already replaced both 02 sensors just to see if that would work and it didn't. So now I'm just closing my eyes and trying to point somewhere that may be the cause.
