Hello I recently bought a used 2005 Acura MDX touring With a little over 215k. A few days after I bought it the CEL gave a DTC P0420. My mechanic says it means one of the catalytic converters need to be replaced. And that the part runs anywhere from 1200 to 2500 to be compliant with California emissions laws. On another note, I also own a 2002 Acura RL that I blew the engine on. That I've been rebuilding as a show car. My question is since both vehicles have a 3.5l VTech engine are the exhaust systems the same? If so could I theoretically replace one of the catalytic converters from the MDX with one from the RL, since I know the RL cats are good? If this is not a possibility can you point me in the right direction towards fixing the P0420 DTC that's not as hard on the pockets as replacing the catalytic converters? And yes I did search through the forums to find an answer or at least a general idea. Thanks for your help.

 

You can go aftermarket but those tend to fail very quickly.

The code could also be due to a bad sensor, did they move the sensors around to verify the problem stayed on the 1 bad cat?

Parts catalog says the RL and MDX have different cats so that won't work either.