Rep Power: 0

Okay, its a 2007 hybrid with 230k miles on it. It runs well but eats oil. I got a check engine light and the code was P0420. I checked the temperature Prior to the Cat and it was just below 300 degrees. After the Cat it was around 500 degrees. Those readings make me think the Cat is doing its job? Could it be 02 sensor and not bad Cat?

 
Rep Power: 222

Honda computers are really picky about the cat, my guess would be the cat. You can try a bottle of catalyst cleaner, I had an intermittent p0420 on my gold 05 and it cleared it up