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Old 11-29-2009, 12:28 PM   #1
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Is that always a cat failing? Need to know before I spend the money on a new exhaust system next week?

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Old 11-29-2009, 12:33 PM   #2
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It can mean a cat failing, engine coolant sensor, exhaust manifold leak or an O2 sensor. See https://www.gmforum.com/t284086/#post1390979
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Old 11-29-2009, 12:50 PM   #3
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Thanks, I will have the 02 sensor scanned before I replace the exhaust. I don't think it is an exhaust manifold leaking.

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