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Returning P0420


Topic starter

My 2013 Ford taurus police interceptor 3.5 has had bank 1 Catalytic converter replaced has had both rear bank 1+2 oxygen Sensors replaced and a full diagnostic scan showing that there's nothing wrong with the systems cleared the code and 2 days later it was back.Please Scotty anything that you could help me with.        THANKS P.McGrattan.









2 Answers

Who did the "full diagnostic scan" and where was it done?  Something upstream of the CAT is causing the p0420 code, usually oil burning or an overly rich mixture.  I would find an alternate, qualified independent mechanic to use a high end scanner to check for codes and go from there.


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