I have a 1999 Acura TL. I have been trying to get my check engine light to get solved so I can get my car registered. I recently had a code come up for my EGR valve. I cleaned out the port and passageways that were full of build up. That didn't solve the problem so I bought a brand new EGR valve for $85.00. I cleared the code but sure enough an hour later while driving my car the check engine light came back on. I read the codes again and the code P0420 came up. It says "Catalyst System Efficiency Below Threshold (Bank 1)" What does this mean and how to I fix the problem without having to buy a new catalytic converter. I'm a collage student and don't have the money to do that. Thank you!