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Repeat check engine light for right bank cat threshold low.

Discussion in 'Chevy Tahoe Forum (GMC Yukon, Cadillac Escalade)' started by M-technik-3, Jan 25, 2014.

  1. M-technik-3

    M-technik-3 Member

    So I have done all four o2 sensors and the light will go away for roughly 150 miles then pop it comes back. I have replaced numerous normal wear and tear items. Plugs and wires, o2 sensors, IAT sensor and air filter and fuel filter. I have also cleaned the MAF with CRC cleaner.

    It has a minor stumble but still is getting about 17 mpg. Not happy with stumble, I think I have to check for a vacuum leak next but the Cat issue bugs me.


    I do not want the expense of replacing a cat converter in a vehicle we mainly only use for winter and for towing our race car and beach days.

    Thoughts? Oh Mine is 2002 Tahoe LT with autoride and E85 5.3L with 165K miles.

    Thanks Greg
  2. Conlan Rose

    Conlan Rose Super Moderator 1000 Posts

    If you have replaced all that then it leaves the problem either being the CAT or an exhaust leak. BTW check amazon for the price of a CAT and as long as you don't live in Cali the cheapest one is only $60.(http://www.amazon.com/Walker-15053-...r=2002|2002&carId=018&n=15684181&s=automotive) That's alot less than the previous gen of truck CATs. Just use amazon's part search tool and you can find the part for cheap.
  3. M-technik-3

    M-technik-3 Member

    Yeah, no leak in exhaust. Guessing it is the cat then, wondering why it's failing. That's cheap for a cat. Their size has drastically shrank over the years. In my early BMW's they are 3x the size of what the Tahoe has.
  4. Conlan Rose

    Conlan Rose Super Moderator 1000 Posts

    CATs have become extremely more efficient as time has gone on. At this point CATs barely cause any restriction in the exhaust like the olds ones did. They also have gotten cheaper because of competition between exhaust manufactures.

    Why is it failing, heres a few possibilities:
    1. Coolant or oil leak in to a cylinder that burns the fluid which can clog or damage a CAT
    2. Excessive vibration, heat and time can damage the catalyst or break it down causing it not to work.
    3. It may just be used up. The catalyst does not last for ever over time it will be used up and no longer be able to absorb/convert as many elements as when new. The ECM is smart enough to know when the CAT is well beyond the specs.

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