Hi All :

My car is throwing a PO138, which is a bank 2 O2 sensor failure. This relates to the senor after the CAT.

My question is...could the CAT be bad and how would you know ? It seems logical that if the after O2 senor is detecting improper O2 levels and the before O2 senor is fine, it might just be doing it's job and declaring failure.

Anyone out there had any experience with this situation.

Thanks to all who reply !

smartypants.

 

c'mon smary,, you know codes are clues-- not diagnosis by themself

you can do an electrical test of the sensors to see if both are working right
Go to a muffler shop and ask for a cat test
In the States they will ck its temp and flow rate,, for free most times

smell your exhaust--rotten eggs? bad cat

 

I agree that the codes aren't always helpful and I'm really tired of chasing down bad sensors. I'll review the manual for the O2 sensor electrical test.

OK.....so if the CAT is bad it will restrict flow and run hotter than usual ?

 

Smarty. Do a continuity check before u go buying a cat. Sometimes a bad ground in the 02 circuit will throw that code. Ur cat will not fail unless your car is rung rich or burning oil, along with other more rare cases.

 

if the cat fails it typically clogs the beehive like structure of its core
result is engine wont rev freely

O2 sensor testing is next

 

How many miles? Test the o2 sensor(s) first. They live in a tough world.
Not to many cats go before the sensors unless due to mods.

 

99 with 90K miles. Car is completely factory.

I'm not sure, but the car seems to have more exhaust noise lately leading me to suspect the CAT. How long does the exhaust on these cars last ?

So, I'm thinking the sensor.

smartypants.