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Intermittent Check Engine Light P0420

Old 11-17-2012, 10:26 PM
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Join Date: Nov 2012
Location: New Jersey
Posts: 1
Default Intermittent Check Engine Light P0420

Hi All,

I have 2007 Honda Accord VP 4cly manual with a check engine light that comes on for a few days and then turns of for a couple weeks. When the light goes on, I went to Autozone to get it checked and they say its the P0420 code "catalytic converter inefficency". I even had the dealer do a diagnostic and they said the samething. Although I am not convinced. The car does not idle rough at all. And notice not performance degration. In fact, I even cleaned my throttle body, air mass flow sensor and injectors and seen a performance boost.
  • Why would the check engine light go off?
  • While the O2 sensors have their own codes, could it really be an O2 sensor malfunction causing a faulty catalytic converter code?
  • Also I use premium (93 octane) gas. Can this be an issue?
Old 11-18-2012, 10:22 AM
poorman212's Avatar
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Join Date: May 2010
Location: Youngsville, NC
Posts: 11,819

The code does point to the converter. I would inspect the exhaust system for any leaks in the system as this can cause the readings between the two O2's to be out of spec.
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