Re: Heated or not O2 sensor

[Shannen Durphey <shannen@grolen.com>]

(1) use a good voltmeter to measure the O2 voltage.  You'll need to
measure the voltages while the problem is happening.  Look for a
trend, ie voltage fluctuates less and less until it stays around .45
VDC.

GM electrical and emissions manual does tell how to diagnose an O2
sensor.  Guaranteed.  I'd guess you're looking at the page for code
13, or the key on/engine off voltage page.  Yes or no, you need to do
some reading to understand how the sensor works and how to test it. 
The sensor needs to be at a minimum temperature, and it's voltage will
swing from one end of a range to another.  That should be enough to
get you started.  I know from experience that giving out the answer
will keep a person from learning to use the manual.  I'm working next
to an apprentice mechanic, and I'm watching him go through the same
thing. : )

(2)  Buy a scantool and use it to read the O2 voltage.  This is the
easiest way.  If you don't own a voltmeter, a scantool might be the
the cheaper option.
Shannen

lpwcruzr wrote:
> 
> Well I might sound like an idiot but,, How do I do this? My electrical and
> emissions manual has nothing in it on how to diagnose an O2 sensor. All I
> can find is the wiring diagram. It shows what looks to be 45volts in the PCM
> at the O2 sensor input. Do I need a scan tool at the ALDL for this, or can I
> check any of this with a volt meter at the O2 sensor??
> 
> Paul Washburn
> lpwcruzr@netzero.net
> 
> > Take a look at your idle o2 voltage and see if it seems right.  Even
> mounted
> > in the manifold, after a long idle my truck would go into open loop
> because
> > the sensor did not warm up enough.  I sued a 90 ford 5.0 sensor and it
> works
> > fine.
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