catylic conv.

[basilv]

hey guys
my check engine light came on with 2 codes the camsensor set point not reached and bank 1 is below thresh hopld.. I called the dealer to see if my catylic converter is under warranty till 80k wich it is ,but they tell me that code could also be a oxegen sensor,and if they test it and its the o2 sensor I would be charged a 95 dollar diagnostic fee ,I have personally never seen the code (below threshold )be anything other than a cat ,as i explained this to the dealer they said because my car is a 2001 that system throws the same code for an o2 and a cat.Could this be true? the cam sensor makes it run rich but wouldn't an o2 sensor have its own code?

[Grangalan]

prolly your sensor if its the stock CAT.

[quattro16]

Explain to me how are they going to know if its the 02 or the cat. 95% of the time its the cat.

[whoace]

Explain to me how are they going to know if its the 02 or the cat. 95% of the time its the cat.

You take a sample of the exhaust gases before and after the cat to determine cat efficiency. That coupled with a scanner to log o2 sensor activity.

[Nebone]

Is it the P0420 code?

This code gets thrown by the secondary 02 sensor which measures catalyst efficiency.

So what to log in order to find out if its the 02 sensor?

[djwimbo]

They can determine if it's the Cat or not by monitoring the oxygen sensor's cross counts and the exhaust back pressure. If the shop has IM240 equipment or any emissions test equipment they can test with that as well.

A clogged cat can have >6psi in the exhaust before the cat under WOT as well as very low exhaust velocity at the tail pipe. Normal is 1-3psi. A clogged cat will also increase exhaust temps drastically.
An failed cat normally will smell like sulfer/rotten eggs, etc.

NTM if it is the post cat oxygen sensor, there's a number of codes it'll throw if it's the failure point. Slow Repsonse, Heater Circuit Malf, Open ciruit, ...