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Oxygen sensor??
Topic Started: Feb 5 2010, 02:43 PM (738 Views)
DirtyWhiteBoy
Fresh Fish
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I have a 1996 Geo Metro LSI with 1.3L, 5sp with 160k miles on the car. The other day I borrowed a friends code reader to diagnose a "service engine soon" light and came up with the code "catalyst system efficiency below threshold (Bank 1)". I'm guessing that the code is a bad oxygen sensor but want to make sure before I buy the part. Could someone please tell me what that code is? Thank You
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Memphis metro


This is about the best I can do for you,

http://www.obd-codes.com/p0420


Did you clear the code and see if it came back? Sometimes it is just a one time deal and may never do it again. And sometimes it comes right back, indictive of a real problem. Check the things listed in the website above.


Oh and one other thing, Take a bath! Dont be no dirity white boy!
Edited by Memphis metro, Feb 5 2010, 02:49 PM.
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DirtyWhiteBoy
Fresh Fish
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Thanks for the reply. Yeah, I cleared the code and it came back the next day so I'll check the things in the link you posted
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Johnny Mullet
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Fear the Mullet

Sounds like a bad cat converter.
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mwebb
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FOG

Johnny Mullet
Feb 5 2010, 03:03 PM
Sounds like a bad cat converter.
it certainly does

in fact there is nothing here to indicate any problem with an 02 sensor at all .

having said that
if the front 02 sensor is not cycling fast enough rich to lean in 100ms and lean to rich in 100ms when hot at 2k rpm ....

it may contribute to a P0420
in a marginal cat , as the cat has to store the gases until the 02 sensor changes state .
you would need a scope on the 02 sensor signal to confirm that
and
IF that was found to be the case , there is no way to guess IF the 02 sensor replacement
(with a new OEM or GM part)
would help the marginal cat converter to pass the self testing in the system .

either way
the old cat will still be "marginal" at best.
===================
if you have the use of a better scan tool , look at Mode 6
if
all Mode 6 tests have passed and you have a P0420 and no other DTC the cat is bad
IF
all Mode 6 tests except cat converter have passed and you have a P0420 and no other DTC
the cat is bad .

the farther the cat test result is away from the max or min limit
the better is the condition of the cat , if the test is a pass but very close to the min or max limit ,
the cat is marginal and will alternate pass and fail as the test is run during the operation of the car,

misfires and or crap oil and or stuck PCV valve and the use of premium (mediocre) fuel
may contribute to the early death of the cat .

google "GM MODE 6" search for your car for more info on Mode 6 for your system
Edited by mwebb, Feb 5 2010, 06:15 PM.
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Bad Bent
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Facetious Educated Donkey

Welcome to the forum, DirtyWhiteBoy! :coffee

:lol Bath, as in wash my Dirty White Van, not!

My Wife's '96 had the dreaded P0420 and I used my trust code reader to clear it. :D It returned, I cleared it. :) It returned, I cleared it. :ermm: It returned, I cleared it. :( It returned, I cleared it. :banghead An new $120 Magnaflow stainless steel Catalytic converter fixed it. :banana
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