What do these codes really mean?

My MY2000 is throwing these two CEL's repeatedly: p0430 catalytic system efficiency below threshold for bank 1 and the code for bank 2. What exactly is this telling me? Cat's are worn out? Other than putting tape over the light (lol), what do I need to do? I'm guessing that this is fairly common? Thanks! Bill

P0430 means your bank 2 after cat O2 sensor is detecting that the cat is not doing the job it should be and might be time for a new cat. If you are also getting P0420 then your bank 1 cat could be going as well. I would post the exact (other) code you were getting (kinda unclear from your post) and model year of your car in order to get more detailed info. I would clear the codes and see if they reappear.

I am getting both p0430 and p0420, sorry I wrote that poorly. I cleared the codes and got the light again within 20 miles. thanks

If you're not getting any other codes and they re-appear, I would say your cats are probably toast. How many miles? What kind of cats? OEM? Have they been replaced before? Are you using stock/orig O2 sensors?

From rt.org: P042(3)0 TWC conversion, bank 1(2) - above limit Possible fault cause - Oxygen sensor ahead of and after TWC exchanged - Valve lift fault - Aged oxygen sensor after TWC - TWC faulty

I can't know for certain how many miles, but likely around 134,000. They are OEM cats. I also don't know about the o2 sensors. I bought the car with a replacement motor that has around 90,000 on it now and have no idea if they are original or replacements. What is rt.org?

There is a an 8 year/80k mile emissions warranty in the USA, but unless your cats were already replaced within that timeframe, I don't think you would be able to argue for another set of replacements, and even then... the car is 4 years and many miles over that limit. 134k is a fair bit of miles, but cats can last longer than that for certain. They can also go before then. O2 sensors are probably telling you the right thing as they rarely fail (pricey too, at ~$70 each), if you have a Durametric or other OBD2 reader you can monitor their readings to validate they are reporting accurate info, if you see the same numbers from pre and post O2 sensors then your cats are toast. You could pick up used cats or new ones... rt.org is renntech.org, lots of technical info there, this place has tech info too but not as readily available or as organized as it is on renntech.org.

Logray, Thanks a ton for the info. I do have an OBDII reader and will look at the O2 sensors.

Quotes source post: 9398955

Just to add the codes point to converters (both sides) operating below efficiency. Now in some cases -- I have not double checked my sources if this is the case for your car's DME -- an error on one bank will trigger error codes for both banks. My 02 Boxster has produced a P0430 more times than I can count and yet I've only seen one time (and I can't remember anything special about this one time -- check that... misfires when I started the car in cold/damp conditions after it sat for a few days) when I read the code I found both P0430 and P0420 codes. The Obd reference says -- in so many words -- that if any O2 aging codes are present to replace the O2 sensors indicated by the codes, clear the codes, and drive the car some more to see if the converter codes reappear. If they do... Or if there are no O2 aging error codes the converters are toast. But toast is a relative term. I've managed to 'nurse' my 02 Boxster with its under performing converter now for more than a few years and through a few smog tests. I run a good (approved) oil. I change/have it changed every 5K miles. I change the plugs when they are due sometimes a bit earlier. I buy a top tier gas from a busy station. Now believe it or not I've found the Boxster and this weak converter sensitive to 'supermarket' (discount) gas. A few times when gas prices got so high and I stopped buying top tier gas the CEL was on quite often and always it was P0430. When gas prices dropped and I switched back the error code stopped appearing nearly so frequently. Since then I have stayed with top tier gasoline though of course seeking out the stations that offer their gasoline at competitive prices. Also, what seems to cause the error code to appear more readily is colder weather. We've had nice weather here up until a week or so back then it turned cold (well what passes for cold here) and wet. Sure enough even though I'm running top tier gas (Shell mostly) and driving the car the same way as always, the CEL has come on twice when I went months before without seeing it. I know the converter likes hot weather so when it comes time to smog the car -- and it is due this May -- I pick a 'hot' day to take the car in. What you can try, if you want in whole or in part, is if the plugs are in need of changing change them. Change the engine air intake filter too, if it is due. Keep the oil fresh -- I adhere to 5K mile oil/filter servicing sechedule -- and do not overfill the engine. Switch to a top tier gas and buy from a busy station. Run a bottle or two of Techron through the gas tank, following instructions on the Techron bottle, then after you run the last tank down to say 1/4 tank or so, do an oil/filter service. If there is any way the converters can be 'resurrected' the above will do it. But no guarantees. That the error code came on so quickly after you cleared it suggests your car's converters are in worse shape than my Boxster's converters, which BTW have over 253K miles on them. Sincerely, Macster.

Macster, Thanks for taking the time to write that! I installed an EVOMs air box yesterday and have now driven ~ 80 miles and no CEL yet. We'll see how that plays out. I think you make a good point about the gas, I'm in that business btw, and I've always tried to run premium for a major refiner such as BP. At one time, AMOCO's (BP) premium additives were second to none but I'm not sure what they do these days. I appreciate all feedback on this. Thanks. Bill