[Shop-talk] O2 Sensors

[John T. Blair]

At 09:05 PM 9/14/2011, eric at megageek.com wrote:

 >OK, car is a 2003 Toyota MR Spider.  The "Check Engine" light came 
on, again, for the 2nd O2
 >sensor.  (This will be the 4th one on the car with less than 110K 
miles on it.) Each time, its the
 >same O2 sensor (the one at the end of exhaust system)

 >First, what could cause this car to constantly kill the same O2 
sensor but not the one
 >upstream' from it?

Moose,

Not sure why the downstream one has failed twice in 110K, that's a 
bit unusual.  I've got O2 sensors that have been in my cars for over 200K.

When you pulled the sensors, did you inspect the wires?  Was the 
insulation melted?  If the wire
is able to touch the exhaust pipe, cat, etc. then the insulation can 
melt and the sensor short out.

When did you have to replace the 1st O2 sensor?  If it was about 55K 
miles ago, then that's an
even distribution.  If the were both at 100 and 110 then, that's a 
different story.  It could be that
the 2nd O2 sensor we defective.  Then Cat. converter could be failing 
can causing the new O2
sensor to fail.

It's also possible that the O2 sensor hasn't failed.  If there's a 
problem with the cat. then that would cause the down stream sensor to 
read off.  If the engine control module (ECM) can't correct the 
mixture to get the down stream O2 sensor to read corrrectly, then it 
throws an O2
sensor error.

 >Second, could any additional damage occur from not fixing it right 
away?  (We plan to write to
 >Toyota to have them give us an answer since the first 3 times this 
car was under warrantee.)

I don't think so, with the exception of possibly a little more 
pollutants.  The burning is all done,
and the ehxaust is on it's way out, but contains to much or too 
little Oxygen in it.

But I wouldn't wnat to run 100K mi. before trying to fix it.

You might also want to get on a Toyota forumn for the car, and see 
what type of problems
other have had like you are having.

John



>Thanks in advance!
>
>Eric P
>"Be as beneficent as the sun or the sea, but if your rights as a rational
>being are trenched on, die on the first inch of your territory." Ralph
>Waldo Emerson
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John T. Blair  WA4OHZ     email:  jblair1948 at cox.net
Va. Beach, Va
Phone:  (757) 495-8229

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