1962 Mazda 626

I have a Mazda 626 96, 4Cyl, 2.0 Lit engine with 121,000 miles on it. The check engine light comes on when I have half tank of gas and stays on till fuel indicator comes on. On filling the tank up it goes off after driving 10-12 miles. I had the code intepreted at the local AutoZone and it is P0421 saying that it has a running below warm thershold value and has a bad catalytic converter. Auto Zone guy says if that is the problem then the light should always be on. I have read about problems with the fuel caps on Japanese imports. I am looking at other Mazda owners if they have encountered anything like this and possible solutions that they successfully implemented
July 3, 2007.

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