heimanman Posted December 1, 2005 Share Posted December 1, 2005 Hi all, I am not familiar with cars, other than checking engine oil, fluids, filling the gas tank, and driving. My 98 Corolla engine light came on and it was diagnosed with the Code P0420. On the machine, its description is Catalyst Efficiency Below Threshold (Bank 1). I went to AutoZone see if they know what it is, they have no idea. My cousin told me that it tells me I have to change the Catalystic Converter. How can I ever find out ? Can anyone help me please? Thank you. Quote Link to comment Share on other sites More sharing options...
fidgits Posted December 2, 2005 Share Posted December 2, 2005 Well, from your description, it certainly is the cat... it may just need a clean, or it could need replacing.. the good news is it doesnt sound serious, so unless you have a smog test coming up soon, i wouldnt worry too much! Quote Link to comment Share on other sites More sharing options...
stevelaw Posted December 3, 2005 Share Posted December 3, 2005 Don't rule out a BAD O2 sensor here---the one behind the cat converter. Test it. See if you get steady voltage of about 200 Mv. If you get a varying voltage that's not steady, then you probably need to replace the cat convertor. But then again, the O2 sensor may not be reading correctly. Got a voltmeter? Quote Link to comment Share on other sites More sharing options...
JCTurbo Posted December 22, 2005 Share Posted December 22, 2005 Well, from your description, it certainly is the cat... it may just need a clean, or it could need replacing.. the good news is it doesnt sound serious, so unless you have a smog test coming up soon, i wouldnt worry too much! it's possible the rear O2 is also bad, but it wouldn't cause this code, if the rear O2 is bad it's because the Catylyst has no longer doing it's job effectively Quote Link to comment Share on other sites More sharing options...
tstottle Posted December 27, 2005 Share Posted December 27, 2005 Hi all, I am not familiar with cars, other than checking engine oil, fluids, filling the gas tank, and driving. My 98 Corolla engine light came on and it was diagnosed with the Code P0420. On the machine, its description is Catalyst Efficiency Below Threshold (Bank 1). I went to AutoZone see if they know what it is, they have no idea. My cousin told me that it tells me I have to change the Catalystic Converter. How can I ever find out ? Can anyone help me please? Thank you. We have something in common, unfortunately! I am also unfamiliar with cars and my 02 Toyota Camry CEL light is showing this code PO420, with the same description. Were you able to get it repaired? If so, how was it resolved. Any information you can share with me would be most helpful! Thanks, Quote Link to comment Share on other sites More sharing options...
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