Catalytic Converter Problems On Honda Civic Hybrid 03

Question: Catalytic Converter Problems On Honda Civic Hybrid 03,
I have an 03 Honda Civic Hybrid. It has 122,000 on it. I had an emission test done in 01/08 and passed. I had the 120,000 service a month ago and everything was fine. They said something about the throttle sticking and did a fuel injection. Mind you I’ve had a rattling noise under my car when I first start it each morning for two years now-took it to three dealers and they all said, oh the car is old-that noise is normal. A month later after my 120k checkup (may), my check engine light comes on and my catalytic converter is fried. How can I pass emissions in January, and have a good 120,000 service report in April,and a month later in May my CAT is fried? 3 years ago, honda updated their software because they said they a software malfunction was making the fuel burn lean and could cause the Catalytic converter to fail. I don’t know if any of this is related, and I know my car has a lot of miles on it, but how can my catalytic converter just fail one day? Thank you.

Best answer for Catalytic Converter Problems On Honda Civic Hybrid 03

your catalytic converter is not “fried”. The reason the check engine light came on is that the ability of the catalytic converter to process exhaust gases through the chemical conversion of pollutants to harmless tailpipe emissions has deteriorated to a point where it has less than 50% of its original ability to process the exhaust gasses.

the process of turning harmful exhaust gasses to harmless exhaust emisions is a chemical process. The catalytic converter has ceramic pellets or a honeycomb that is coated in precisious metals that, when they come in contact with hydrocarbons or oxides of nitrogen cause a chemical reaction that changes those hydrocarbons to hydrogen and carbon dioxide and change the oxides of nitrogen to nitrogen and water.

As long as there is a coating of the metals on the honeycomb the chemical reaction process still occurs. Because there is a chemical reaction, over time the precisious metals are depleted or consumed in the process. In your case, it took 122,000 miles to use up 50% of the original precious metals. When the quantity of reactive metals drops to that level the catalyst is slower to convert the gasses. It will still pass a smog test. As the converter continues to diminish in its ability to convert the exhaust gasses the tailpipe emissions will rise to a point where you will no longer pass a smog test.

the federal EPA decided that when the ability of the converter to process the exhaust gasses drops to under 50% of its original capacity that the check engine light has to be turned on and the converter should be replaced.

the car is not going to stop on you. I guess if you wanted to you could drive the car without incident until the next time you need a smog test. It will not pass a smog test with the check engine light on.

hope that helps explain your conundrum

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