CEL for both cats

[dionh1117]

Hey I recently bought a 2004 a4 3.0 and a week after driving it the CEL came on. Got it scanned turned out both cats are gone. Is there any real damage from not changing the cats besides fuel economy? And has anyone ever put a straight pipe on ? Does that make it obnoxiously loud? I'm new to the Audi scene so all feedback would be appreciated. Thank you


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[tHatOne guY]

The worst case of failed cats I've seen, they were completely clogged and would not allow the engine to even start and idle. No idea how long that takes but other than that occurrence I don't see it causing any other damage.

[dionh1117]

The worst case of failed cats I've seen, they were completely clogged and would not allow the engine to even start and idle. No idea how long that takes but other than that occurrence I don't see it causing any other damage.

Thank you i just bought the car so finding the money to buy new ones will have to wait. Cheapest one I saw was 450 for one. Smh


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[Kevin C]

Hey I recently bought a 2004 a4 3.0 and a week after driving it the CEL came on. Got it scanned turned out both cats are gone. Is there any real damage from not changing the cats besides fuel economy? And has anyone ever put a straight pipe on ? Does that make it obnoxiously loud? I'm new to the Audi scene so all feedback would be appreciated. Thank you


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I usually takes a while to get a CEL. Pretty sure you now know why the car was being sold. My 1.8T was getting a CEL for low cat efficacy. At first clearing the code would hold me for a few months. After a while, it would only last a couple of weeks. No clogging, it was just that the catalyst was no longer working well enough.

A newer cat solved the issue.