2003 Pontiac Grand Am Catalytic Converter replaced, but cod

Tiny
LILSEANY
  • MEMBER
  • 2003 PONTIAC GRAND AM
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 104,000 MILES
My state requires that you pass your emissions test every year on your birthday in order to renew your tag. (This is the case for most states right?). Last year I could not pass because my check engine light was on. The only OBD II code my car gave was P0420, meaning the catalytic converter was faulty. I paid $300 to have a new one put on along with an O2 Sensor and the light came off (I was told I had to get both of those parts changed). I went back for another emissions test, but the emissions people told me I could not pass because my car needed to go through a few drive cycles to make sure the light doesn't come back on. I drove around for a few days and the light never came back on and I eventually wound up passing the emissions test 3 weeks late. Unfortunately, about 3 months later my check engine light came back on and low and behold it was the same P0420 code for the converter. When I reset the codes, the same code would come right back on after about 10 minutes. The original mechanic will not give me a refund because he said I have not kept up with my tune ups which conveniently for him also cost $300. So now that it has been a full year again and time for emissions, I do not know what to do. Do I really need to buy a whole new converter again? Is it possible the wrong type of converter was put on my car? Can the code be coming up for some reason other than the converter or O2 sensor? It's so weird that the converter code came back up so quickly.
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Thursday, July 30th, 2009 AT 12:47 AM

7 Replies

Tiny
DOCFIXIT
  • EXPERT
Hi
With no other codes present the 420 by itself says CAT has degraded. See this alot and it maybe what has happened to you. If and aftermarket CAT was used instead of OEM they fail. Check to see what was installed. Only other things that can damage CAT is antifreeze leak internal, oil level to high, repair of engine and silicone used that got into cumbustion chamber, misfire or leaking injector. Have you had any of these events?
Let me know
Thanks for donate
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Thursday, July 30th, 2009 AT 8:17 AM
Tiny
LILSEANY
  • MEMBER
Thanks for the reply!

No, none of those things you mentioned has happened over the last year, but something did cause the P0420 code to come up in only 3 months after putting the new converter on.

I do remember asking a different mechanic about it and he told me the 'wrong' type of converter for my car was put on. He said it was an old type. I didn't really know if I should take him seriously, but it sounds like what you are saying about the aftermarket CAT vs. The OEM. (What's an OEM?).

I wonder why the converter that was put on let me pass at all then before it caused the code to come back up.
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Friday, July 31st, 2009 AT 4:00 PM
Tiny
DOCFIXIT
  • EXPERT
OEM is GM manufactured CAT and if aftwer market was used that is why it failed
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Saturday, August 1st, 2009 AT 2:52 PM
Tiny
LILSEANY
  • MEMBER
Well. Since my tag/emissions is coming up in 2 weeks I broke down and paid the $450 to get a new converter and o2 sensor put on earlier today. They turned the check engine light off for me, but before I even got home it came back on with the same P0420 code. The lady at the shop said they'll take a look at it and switch the converter out again, but I'm really getting tired of this! :( :( :(

I'm not getting any other codes and my engine is running good. The converter and the sensors are brand new and the code keeps coming back. I really don't know what to do at this point
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Tuesday, August 11th, 2009 AT 3:35 PM
Tiny
DOCFIXIT
  • EXPERT
O.K. They are not using a Gm convertor GM part number 22712078 at $569.96
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Tuesday, August 11th, 2009 AT 3:56 PM
Tiny
LILSEANY
  • MEMBER
Yeah, I thought the price seemed to good to be true. I actually made an assumption that the light came back on because of the P0420, but it was actually P0134 and P0135 saying the front O2 sensor was not responding. I went back and the guy said he somehow managed to forget to connect the sensor properly. He fixed it at no charge and then got my light off again. So far it's been off, but I guess we'll see. Hopefully I will at least be able to pass my emissions before it ruins the cat again. Thats how it happened last year. It gave me a couple of good months before going out again. If that happens, I'm going to HAVE to get the GM part.
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Tuesday, August 11th, 2009 AT 7:17 PM
Tiny
DOCFIXIT
  • EXPERT
Glad to hear now you can get tags. Maybe this CAT will last longer good it was O2 sanfu and not 420. Good Luck
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Wednesday, August 12th, 2009 AT 8:01 AM

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