Rep Power: 0

Put my honda on a diagnostic machine and the code P0420 popped up. Catalyst system efficiency below threshold bank 1. I am going to replace the oxygen sensor myself, where exactly is this oxygen sensor located?

 
Rep Power: 812

should be in the cat. but it sounds more like a problem with the cat converter than with the sensor.

 
Rep Power: 256

P0420 is a cat problem not the sensor.

 
Rep Power: 0

thanks gearbox and lowlife, you were both right. After looking a little bit more i noticed that my cat. converter and manifold were cracked. Is this easy to replace? I looked at it and it looks like the whole assembly is fairly easy to remove and put a new one on. I have found assemblies ranging from $270 - $620. Is there anything that I am not seeing that you might know?

 
Rep Power: 275

probably not, cracked cat will throw that code

 
Rep Power: 812

may want to see if its possible to weld the crack shut on the old one before spending $$ on another manifold. any shop that has welding equipment could take a look and tell you if the metal can be safely welded. the oem one has alot of problems and a replacement will likely have the same problem. they have aftermarket pieces, but who knows what kind of quality those have, or how good their generic cat is. for a short term fix, if it cant be welded, you might try that muffler mend putty at the auto store. ive used it to fix small holes in the exhaust before and it works great. same with metal weld epoxy. make sure to check the temp rating on the package because it needs to handle extreme heat.

 
Rep Power: 275

how many miles are on the car cause I think all emmission equipment has warranty till 130K and is it an ex or another trim