Can P0420 not be the catalytic converter
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Cadillac SRX First Generation Forum - 2004 - 2009 Discussion, Can P0420 not be the catalytic converter in Cadillac SRX Forums; I have a P0420 code and an appointment at the dealer under warranty. Has anyone had this not be the ...
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    Jim_V is offline Cadillac Owners Fanatic
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    Can P0420 not be the catalytic converter

    I have a P0420 code and an appointment at the dealer under warranty. Has anyone had this not be the catalytic converter?

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    The Wrench is offline Cadillac Owners Enthusiast
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    Re: Can P0420 not be the catalytic converter

    Well, it could be the rear O2 sensor is bad, or maybe a big leak in the exhaust pipe just behind the converter; but not too likely. The only thing the system does is read the rear O2 sensor, and compare it to the front sensor. If the rear sensor reads differently, and fluctuates at a much slower pace, then the system deems the cat to be functional, Any other problems will be seen in the performance of the front sensor, and will set a code for that. Probably 95% chance it's the converter.

    DG

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    Jim_V is offline Cadillac Owners Fanatic
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    Dealer said cat is bad but they also found misfire and lean codes. They reset the codes and since the light came on and went off 3 times but only code is P0420 bad cat. Taking it back for a new cat they just want to make money for anything they can since I have 200k warranty on cats. I'll pY them to clean injectors if that makes them happy.

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    frankcottnj is offline Cadillac Owners Member
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    Re: Can P0420 not be the catalytic converter

    yes, I ignored common sense adn gapped the iridium plugs too big and it fooled ecm into thinking cat was bad.

    frank 2007 srx

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    The Wrench is offline Cadillac Owners Enthusiast
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    Re: Can P0420 not be the catalytic converter

    Hmmmm; yeah, I guess it makes sense that if there was an engine issue that pretty radically changed the exhaust mixture under certain driving conditions (such as a lean or miss condition) it might be possible that the computer would adjust the fuel trims within the allowable 15-20%, and the front O2 sensors would not set a code. But the rear sensors wouldn't function properly as a result of the skewed mix. Hadn't really thought about that.
    I guess a check of the fuel trims on the front sensors under various driving situations could spot the situation. Hypothetical situation; a small vacuum leak causing a lean condition at low throttle settings, but not as noticeable at larger throttle openings. This would cause large fluctuations in the fuel trims as the driving conditions/throttle position changed, and freak out the rear sensors - maybe. Might damage the cat after a while also.

    DG

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    Jim_V is offline Cadillac Owners Fanatic
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    Re: Can P0420 not be the catalytic converter

    Well I have been very busy at work and unable to schedule another appointment but now they say they can't get me in for over a week and my odometer has topped 199K. The CEL came on 5 times since my last appointment and reset itself with no other codes than P0420. The dealer is telling me now that they can read codes that my reader cannot and is just trying to screw me out of a warranty covered repair. I had two service managers one in NJ where I bought the car and a second in MD who were both great. Suddenly I get this new guy and he really is pissing me off. Capitol Cadillac has just lost a customer as I will never go back.

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    Re: Can P0420 not be the catalytic converter

    Quote Originally Posted by Jim_V View Post
    Well I have been very busy at work and unable to schedule another appointment but now they say they can't get me in for over a week and my odometer has topped 199K. The CEL came on 5 times since my last appointment and reset itself with no other codes than P0420. The dealer is telling me now that they can read codes that my reader cannot and is just trying to screw me out of a warranty covered repair. I had two service managers one in NJ where I bought the car and a second in MD who were both great. Suddenly I get this new guy and he really is pissing me off. Capitol Cadillac has just lost a customer as I will never go back.
    Hi Jim_V,

    I received your PM and have responded. I look forward to hearing back from you.

    Have a nice night,

    Austin J.
    Cadillac Customer Care

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    MoistCabbage's Avatar
    MoistCabbage is online now Cadillac Owners 10000+ Posts
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    Quote Originally Posted by frankcottnj
    yes, I ignored common sense adn gapped the iridium plugs too big and it fooled ecm into thinking cat was bad.

    frank 2007 srx

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