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2007 sts-v catalytic converter issues. Should i replace?

13K views 20 replies 11 participants last post by  skipstheboss 
#1 ·
Hey Guys,
i just threw an engine light and the dealership says its a damaged Cat connected to my aftermarket exhaust.
I purchased the extended warranty but they say its not covered.
They want to charge me $150 to replace it since the exhaust is aftermarket.

1. Should i be charged since i bought extended warranty that covers mechanical and electrical?
2. Is it safe to run the way it is (with damage)? This is my first supercharged car, so im concerned that it may hurt the car.

I've gutted the cats in previous vehicles (2000 Trans Am Ws6 and my C6) and it sounded amazing and ran pretty good in my opinion.
Anyhoo i know $150 isn't that much, considering it COULD be a few hundred bucks for the cat replacements.

Thoughts?

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FYI - i should note that the aftermarket exhaust was already installed when i purchased the vehicle.
 
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#4 ·
So I don't know what they are replacing for $150. A new cat for this car I $800+ it's the entire manifold. They are back ordered for months last I knew. And if its the cat I will clog up to the point the car will not run right. So for $150 I don't think it's a cat. I would bet 02 went bad.
 
#9 ·
I was gonna say, Federal Emissions warranty is 8/80.

Was this a P0420 or P0430. These are fairly common GM codes.

My suggestion before replacing catalytic converters, is give the post-cat O2 sensors a good cleaning and/or replacement before replacing the cats. 9 times out of 10, it's a clogged, and/or faulty post-cat O2 sensor first. Basically, the PCM isn't correctly measuring the amount of oxygen storage capacity that the cats have, by comparing it with what the pre-cat HO2S's are reading and adjusting fuel trims. Hence the code.
 
#12 ·


The two sensors in the exhaust in this picture are the post-cat (downstream) HO2S. P0420 usually has nothing to do with the pre-cat (upstream) sensors other than using them as a benchmark. Your PCM monitors this with the post cat (downstream) Heated O2 sensor (HO2S) and it's "switching" in relation to the pre-cat (upstream) Heated O2 sensor's "switching". A properly operating system has the Pre-cat HO2S making large and quick changes, whilst the Post-cat HO2S has a slower "Switch" rate as it trims the fuel curves. When the post-cat HO2S also switches in large increments and fast, this code will set.

Remove them and spray them off with any electronics contact cleaner. CRC Brakekleen will also work too. Stay away from the Wearever stuff (or whatever Advance Auto parts version is), as it leaves a film.

Let dry and reinstall.

I would then disconnect the negative terminal of the battery, reconnect it, and let it re-learn it's idle. For optimum performance follow this GM drive cycle to help re-learn it: http://www.obdii.com/drivecycle.html . This step is more or less like rebooting your PC at home. This resets the PCM to it's base and clears out all the cobwebs and bugs it picks up from time, your driving, etc... It will also clear DTC's that may be present and/or I/M system status runs. This ISN'T a fix. Just letting you start fresh. From here, the PCM will run all it's I/M system tests as well as monitor for faults. If the code comes back, my next step would be actual replacement of the HO2S.

Always start small and work your way up. Start by cleaning them and/or inspecting wiring harnesses/connectors, etc. If that doesn't work replace them. Last thing would be cat replacement and potentially PCM replacement. Problem is, most jump right to those big parts without troubleshooting the little shit before it.
 
#13 ·
Always start small and work your way up. Start by cleaning them and/or inspecting wiring harnesses/connectors, etc. If that doesn't work replace them. Last thing would be cat replacement and potentially PCM replacement. Problem is, most jump right to those big parts without troubleshooting the little shit before it.
What fun is that!? I think the reason many skip right to the big stuff is that many of us are car guys and want our V's to sound like they perform. Gutting Cats and disabling the secondary O2's both stops the error codes and wakes up the sound of the exhaust and costs nothing but time if you already have a tuner or a friend that does. Replacing a O2 is ~$70/ea for parts in aftermaket, no idea on Dealer pricing. If you need actual Cats, $450+/ea aftermarket according to Autozone... At that point even having a shop do a tune is less than the price of a single replacement CAT if that is the failure. BUT gutting cats can make the exhaust a bit stinky with unburned fuel...
 
#14 ·
You're actually NOT eliminating the code though by gutting and/or completely removing them. You're just changing the code type class from a Type A (emissions related major that commands the MIL on), to a Type D or something that is more along the lines of a CAN bus communication code. The code itself is still present though.

I'm a car guy as much as the next, but I also believe in proper troubleshooting/diagnostic processes and having things work properly as opposed to band-aiding crap together and trying to circumvent system(s) unnecessarily for little or no gain, just to say screw you to the "the man" or get a little bit more performance/sound out of something. Yea, the downfall of running gutted/catless is... You stink! The garage stinks! The inside of the car stinks! I don't want that after driving my Cadillac! I know this first hand with my GTO as I run catless. I picked up 5rwhp on a SpeedInc's DynoJet. But I'm tired of smelling like sh*t after everytime I drive it. So I am contemplating putting them (cats) back on.
 
#15 ·
I am being simple for the non car guys here, by error code I was referring to the CEL. It also clears the car to pass the typical (in WA) OBD2 emissions check.

I am with you, while I want more tone and attitude, I am not willing to deal with the stink. Buddy at work has a G8GT with no cats, does sound meaner (course different powerplant with a different cam and thus sound profile to begin with) but it is stinky when he fires up... For the price of OEM or aftermarket V specific cats, if cats honestly are bad, I would think it makes sense to jsut gut the factory manifolds out and install high performance cats form summit, jegs, etc downstream in the Exh... Higher flowing anyway, and then you are ready for TimmyC's headers while still not having smell issue..
 
#16 ·
There are different type classes of DTC's. Some commend the CEL/MIL on, others don't. You can have "pending DTC's", you can have class 2 communications DTC's, you can have a transmission DTC, etc, and you'd not know because the light wasn't commanded on due to the type class of it.

Some places have a mileage since last code cleared counter too. So just turning it off and driving over to the test facility won't necessarily pass you.

Yea, mine is heads/cammed, long tube headers, etc, and yea, it sounds orgasmic, but it's tiring smelling like crap after a cruise. I almost feel like I need to shower.
 
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