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Please help. I have a 1994 Mazda B2300 with 450K miles, and all my recent smog test readings (HC, CO, NO) are high. I suspect the catalytic converter might be the issue. I installed an aftermarket converter (CA) in 2012 when the truck had around 300K miles. I replaced it then because I couldn't pass the smog test. The truck runs smoothly with no other issues. Any advise?
