Re: how to tell if O2 sensor is Bad...

["Dave Ewing" <rabbit16v@prodigy.net>]

I actually haven't checked scirocco.org for this content but if it isn't
there (which I doubt) then this will be very interesting to all.  First,
does anyone know what the 02 sensor actually does?  There is no reference
signal sent to it so how does it create power?  It is a bi metal battery.
It has two metals inside the 02 sensor that creates a voltage.  That is why
you don't use leaded gas in cars with O2 sensors because it would be adding
another metal to the system and cause it to die!!  So, where does it get
it's signal?  The 02 sensor is a sensor that compares one thing to another.
This is the clincher!!!  The O2 sensor compares outside oxygen to the oxygen
in the exhaust system.  The O2 sensor gets the outside (or atmospheric) air
through the black wire!!!  So, if you solder them and wrap them with black
tape or heat shrink, it won't work correctly!!  IF you did it correctly,
bought the correct O2 sensor and used the crimp and heat shrink that it came
with (if you got the replacement single wire that made to fit almost all
single wire applications) then you should be fine since the O2 sensor can
get air through the crimp.  And for those of us who are really cheap and use
used O2 sensors that we find here and there, make sure someone else didn't
solder it or if you graft it into your harness make sure you use the crimps.
Bosch used to get thousands of calls on O2 sensors and why they just
installed one that didn't work so they started coming with crimps and heat
shrink.  This comes straight from the Bosch class I went to (BAPS1) last
week.  Since it was kind of a crash course on D, K, K w/lambda, KE, L, LU,
LE, LH  Jetronic, Motronic, and ABS (all in one week) I don't remember every
little detail, but I am sure other interesting things will surface as the
situation calls for it.  HTH!!!

Dave

>
> >     I just got TT race downpipe and exhaust and want to know if I should
> > change my O2 sensor
>
> I am guessing, since it's been discussed enough, the procedure for
checking
> the output of your O2 sensor is on scirocco.org.  If not, I found it 2 or
> 3 other places.
>
> The thing you MUST, MUST be aware of is how small the amperage is you are
> trying to measure, so don't go half-measure about it...make yourself the
> proper test harness.
>
> I had to try THREE times to get an O2 sensor on my car, correctly.  I did
> two bad solder jobs and that was enough to make it not work.  That's how
> sensistive they are.
>
>
>
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