99 civic cat converter operating below threshold

[jlostj]

ok so i just got a 99 civic. has a check engine light for po420 cat oper below threshold. car runs fine but stalls in park VERY rarely. when i disconnect the battery, the check engine light goes off for like a day or 2 then goes back on. should i A. replace the sensor B. replace the cat C. clean the sensor with alcohol D. Replace the cat ($$$$ ) or E. Drive the car off a cliff and get the insurance money.

[chubbygoatboy]

Replace the exhaust manifold and cat. It is available on Ebay for $153. replace the O2 sensors as well. Sorry, I hope this helps. I realize it is an old post, but I just experienced the same thing!!

[Doug Tatham]

Catalytic converters usually have a lifetime of 150K miles +. Mine lasted 225k miles. If your millage is high, replace the cat. If not, replace the 02 sensors. You can buy generic ones on ebay for $20 each. You should replace them anyway if they are old and you're replacing the cat. If you get the error afterwards, then replace the cat.
I've read that you can rinse a cat with vinegar or lemon juice then rinse thoroughly with water and let it dry and you will "rejuvenate" it. I have serious doubts whether this will work though. As far as rejuvenating the O2 sensors, I don't think anything will work for very long. They wear just wear out.