Catalyst System Efficiency

[jetstream87]

I have a 1997 Nissan Pathfinder LE, today I notice that the check engine light came on in which I connected the OBII and gave me the code P0420 in which I looked it up and the code was Catalyst System Efficiency Below Threshold Bank 1. I drove the car 40 min one way in which at the time I got to my destination that when it came on. Can anyone help me on how can I figure out what I need to diagnose before I blow my money randomly (like buying a new catalyst) so I can pin point the problem. This is my first time doing something technical like this so please be specific, pleases and thank you in advance.

[Hawairish]

The Factory Service Manual: http://www.nicoclub.com/FSM/Pathfinder/1997_Pathfinder/

See EC-219 for the diagnostic procedures.

[smj999smj]

You'll probably need to replace the right bank, upstream, catalytic converter to fix the problem, if you don't have any other stored codes, no exhaust leaks, no vacuum leaks and the engine runs well without misfires. Over time, the catalyst substrate becomes inefficient at breaking down the emissions. This can be detected by the ECM as it compares the readings from the front and rear oxygen sensors on each bank.

[jetstream87]

You'll probably need to replace the right bank, upstream, catalytic converter to fix the problem, if you don't have any other stored codes, no exhaust leaks, no vacuum leaks and the engine runs well without misfires. Over time, the catalyst substrate becomes inefficient at breaking down the emissions. This can be detected by the ECM as it compares the readings from the front and rear oxygen sensors on each bank.

I got no other codes stored just he P0420, so that means new catalytic and the sad part is now that California requires you to have STAR qualified catalytic converter.

[smj999smj]

Rockauto.com sells Walker #81752 for $240, far cheaper than the genuine Nissan part, and it is C.A.R.B. compliant and is STAR certification compliant per Executive Order D-182-52. It is a direct-fit part for the right bank, upstream catalytic converter.

[jetstream87]

Rockauto.com sells Walker #81752 for $240, far cheaper than the genuine Nissan part, and it is C.A.R.B. compliant and is STAR certification compliant per Executive Order D-182-52. It is a direct-fit part for the right bank, upstream catalytic converter.

Well the code went away, no more check engine light, I am not sure what happened.

[smj999smj]

Could have been any of a number of things, such as a sticking fuel injector or a little dirt in the fuel...a small piece of debris getting past the air filter and stuck on the screen of the MAS. Unless it comes back, I wouldn't worry about it.

[jetstream87]

Could have been any of a number of things, such as a sticking fuel injector or a little dirt in the fuel...a small piece of debris getting past the air filter and stuck on the screen of the MAS. Unless it comes back, I wouldn't worry about it.

Thats what I tell myself, I just keep an eye out for it in case it does comes back on. I was ready to buy a new catalytic hahaha good thing I did not get it.

[jetstream87]

Could have been any of a number of things, such as a sticking fuel injector or a little dirt in the fuel...a small piece of debris getting past the air filter and stuck on the screen of the MAS. Unless it comes back, I wouldn't worry about it.

A few months later and the error code came up again