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Discussion Starter #1
I have been dealing with a pesky exhaust leak problem and recently discovered my Catalytic Converter was leaking a fair amount of air at the Flange that bolts to the exhaust manifold. About a year ago the flange weld broke completely and I had to get it rewelded by Meineke. I don't think they did the best job welding the flange (not the cleanest weld) so this time I wasn't going to pay another $280 for them to take off the Cat again and do it over.

I unbolted the Cat myself and took it to a local shop to get it re-welded. My own fault I should have removed the O2 sensor prior to welding, but didn't. The sensor was a good 6" down the pipe, and I know that it deals with a fair amount of heat already.

Now I am getting a Check engine light and Autozone ran their code reader. It is showing Code P0050 which is the upstream one (bank 2 sensor 1).

So it would appear that the welder fried the sensor some how. Just wondering if this is an item where you can save a couple bucks by getting something aftermarket. Is there much difference in quality between aftermarket and OEM?
 

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'05 CTS-V
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8,362 Posts
What year? What engine? How many miles are on the car? When was the last time the O2 sensors were replaced, if ever?

If the pipe was rusted so bad that it failed, it shouldn't come as a surprise that it was difficult to weld it back together. And they charged you $280?!?! :eek: For less than that you could've picked up a brand new cat pipe from rockauto.com and bolted it in yourself.

You can also price out O2 sensors on rockauto.com. OEM upstream sensors are ~$130 online (probably $200+ at your local dealer).
 

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CTS
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256 Posts
You can get them decently priced from AutoZone. Replaced both of mine from the cheapest ones from AutoZone and they work fine.
 

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Discussion Starter #5
Thanks for the replies - car is 2005 CTS with 3.6L and Manual Transmission. 83500 mi.

mattt0305 - Thanks for the link, I think that is the one I will get. You were helping me on my thread a couple months back here:

http://www.cadillacforums.com/forum...orum-2003/521129-2005-cts-3-6-manual-bad.html

Yesterday I got the car raised and had a look at both Cats - they are both leaking right now so there is the exhaust smell I am dealing with. About 18 months ago both had broken while going over speed bumps - just a clean break and I had them re-welded.

So now I suppose I could remove both Cats again and make sure someone does a thorough job at welding them to seal the leaks, or maybe I should just replace both Cats entirely.

Here is where the leak - flange point on both Cats. It is not a rust issue and the pipes are in decent condition. cats.jpg
 

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2007 6 speed manual tarnished platinum
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377 Posts
Ha, both of mine broke too. It more of metal fatigue definitely not corrosion. The second one like 2 weeks after the first. I just went ahead bought 2 new ones. Being stainless steel and the break being on the weld I didnt think trying to get them fixed was worthwhile. The new ones from GM were slightly different and had a different manufacturer name so maybe they'll hold up better. In retrospect I would probably get the magnaflow ones.
 
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