P0420 Fault in 1998 Honda Accord 2.3L 4-Cylinder: Is the Catalytic Converter Really the Problem?
Does a P0420 code mean my catalytic converter (cat) is faulty? My 1998 Honda Accord 2.3L 4-cylinder has 125,000 miles. The secondary oxygen sensor was replaced at 115,000 miles with an original factory part, and the primary O2 sensor remains unchanged. I've consistently used the same fuel type without any additives, and the vehicle runs smoothly under normal conditions. Is a failing catalytic converter merely a symptom of a deeper issue? Can I perform O2 sensor voltage testing using just a multimeter, or do I need specialized equipment like an OBD2 scanner or oscilloscope? I've read on this forum that many aftermarket converters are low quality—does that hold true? Are there any reputable aftermarket catalytic converters worth considering? And finally, are there other maintenance areas I should be addressing to prevent further issues? Thanks, Roach
Most of the time, replacing the catalytic converter resolves the P0420 issue. Cost-wise, it depends on how long you plan to keep your vehicle. I recently saw a 1998 Odyssey owner who installed an aftermarket cat—within just one year and a half, it failed four times. He eventually got his money back and switched to a genuine Honda catalytic converter five months ago. Since then, no DTCs have returned.