O2 sensor damage?

[bcroe at juno.com]

If that light just blips off and back on, your heater was 
continuously powered, just not quite enough for operation.  
If your warmup time is over 50 seconds, you need to put 
some of those parallel resistors across the 1 ohm power 
resistor.  Another way to check this is observe the voltage
across the 1 ohm during warmup to operation.  That 
voltage will hold at 1.25 volts during warmup, then should 
drop back 5 to 20 % (below 1.19 volt) within 30 seconds 
of the LED coming on.  If it is too close to 1.25 volts, you
need more shunting resistors.  Maybe we ought to 
add this to the testing procedures.

If the above works, but the LED still won't stay on, you 
need a bit more voltage.  If you can't  get it from your 
present source, try a pair of wires directly to the 
battery, or the alternator case and output stud.  

There is an outside chance a sensor might be found 
exceeding the regulator current capacity;  a 39 ohm 1/2
watt resistor in parallel with the regulator ought to fix 
that by adding 75 ma.  Maybe a couple will be needed.
I don't really expect this to happen.

Bruce Roe

On Fri, 22 Feb 2002 08:51:34 -0600 (CST) "Gregory A. Parmer"
<gparmer at acesag.auburn.edu> writes:
> 
> So the light may drop out and come back on?  I'll add any details
> you can provide to the assembly guide. The more complete our
> info the better.
> 
> FWIW--mine comes on bright, then dims a bit. The voltage across the
> LED seems to oscillate (faster than a DVM can display). I'm 
> measuring
> at the tailpipe with the Dataq DI-194--neither of which may be 
> considered
> optimal. Readings imply correct function though.
> 
> -greg
> 
> On Wed, 20 Feb 2002 bcroe at juno.com wrote:
> > If you have warmed up the sensor enough to turn on the LED, you
> > are in good shape.  A slight drop in voltage (below 13.5V) may
> > caues the LED to drop out momentarily, but power is still applied
> > to the sensor heater.  No damage done.
> >
> > On the other hand, a complete loss of power to the sensor heater
> > means it should be removed, before damage accumulates.
> > >
> > > and it says there:   "If the LED goes out for any reason,
> > > immediately remove the sensor from the exhaust stream.
> > > The LED indicates the heater is still warmed and active, a
> > > requirement to prevent damage to the sensor."
> 
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