service engine light.

[TwistedArticSS01]

DTC P0422 Catalyst System Low Efficiency Bank 1
DTC P0430 Catalyst System Low Efficiency Bank 2

these are the codes that have shown up. what can i do to fix them and what could cause these problems?

[Tman]

For P0430 = Either your rear passenger O2 sensor is toast or your passenger cat is toast. Quick test would be to reset the code and switch the sensor with the rear driver's side O2. If the code follows the sensor, it's the sensor. If it stays on the passenger side, it's the cat.

Or Could be either a failing passenger side rear O2 sensor or a failing cat (if O2 sensor is ok, then would indicate the CAT isn't doing its job)

Easiest way to tell is to swap the 2 rear O2 sensors and see if you start getting a P0420 instead of P0430, if you do then it's a bad sensor, if you don't then it's a bad CAT

[2001NBMZ28]

I think you meant P0420 for the first code by the description. Since both cats are showing efficiency codes, switching your rear 02's won't work. Do you still have cats?

[SeVeReDiStOrTiOn]

I think you meant P0420 for the first code by the description. Since both cats are showing efficiency codes, switching your rear 02's won't work. Do you still have cats?

That is a very good question

[darsiann]

Could bad mufflers cause my catalytic converter to go bad?

[2001NBMZ28]

Don't think so, they just go bad sometimes. Do you have an exhaust leak close to that sensor? Does it rattle?

[sunsetorangess]

You posted "could bad muffler"s" cause my cats too go bad". How many mufflers do you have?
Any mods done too the car? Its odd that both of your cats would go out at the same time, how many miles are on the car? Try resetting your comp and see if the codes come back.
J