1999 Honda Accord coding P0420

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Apr 12, 2007
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#1
Well I've read numerous forums concerning my issue. Pre O2 sensor, cat, post O2 sensor and every combination in between. I have just over 65,000 miles on the car. Called American Honda and they told me my warranty was 8yr or 80K. Of course mine expired in Feb 07. After doing more research I found a TSB concerning this exact problem.

SERVICE BULLETIN NUM: 03073 NHTSA ITEM NUM: 1000475
COMPONENT: Emission control: CATALYTIC CONVERTOR
SUMMARY: Malfunction indicator lamp is on with diagnostic trouble code P0420 (CATAKYST SYSTEM EFFICIENCY BELOW THRESHOLD BANK 1) is stored. *TT *MJ

I'm curious if this gives a specific corrective action or is just an informative TSB. Anyway any help would be appreciated. If it is the cat, will an after market cheaper cat suffice or should I get the OEM Honda cat. Thanks, mdhonda.
 

Scott

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Nov 16, 2006
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#2
I don't have a lot of experience with this code , I have not had any luck replacing the rear sensor though . I have it on real good authority oem cat is the way to go , in a general sense . I hear aftermarket is pretty marginal or dosen't work from the git go . Hondadude may have some insight on this .