P0420 catalyst system efficiency bellow threshold bank 1 need help with this code. Thanks in advance

 

The bank 1 pre-cat is not doing its job. Bank 1 is the side of the engine next to the firewall. Its possible that the downstream sensor after the pre-cat is bad, but it should throw its own code. Most likely you need a new pre-cat.

 

http://forums.maxima.org/6th-generat...-readings.html

The lacquer thinner works. I have been doing it when I first got the code and throw a gallon in every 6 months.

 

okay thanks guys