SES Light - Bad Cat?

nurseryboy

This past weekend my SES light came one. First thing I did was check the gas cap, and make a few trips to see if it would go off. It didn't. I had an appointment for an oil change today at the dealership, so I asked them to take a look at it too. They came back and said that it's because I have test pipes on my car. I don't, though, haha. They're the ERZ high-flow cats. Of course, they couldn't do anything, but the guy was convinced that the one had gone bad. He was telling me that if it was breaking apart, that stuff could get into the engine and destroy it.

I'm not expert when it comes to this stuff, but I do know that getting a SES light every once in a while with modified exhaust isn't all too uncommon. I've had the cats on the car for about 9 months now and this is the first time I've gotten the light. But, they reset it, and it hasn't come on since in the few little trips I've made. Anyhow.. my question is, is this anything I should be worried about? They gave me a little printout of the "error", and it has on it: DTC RESULTS: TW CATALYST SYS-B1 [P0420]. I'm not sure if that means anything or not.