O2 sensor and white smoke

[Mazda Ebrahimi]

Tom Cloud wrote:
> 
> > Is the O2 sensor supposed to replaced as part of regular maintenance and if
> >  so, how often?
> 
> I read somewhere that the sensors begin to deteriorate (lower output)
> at around 35k.
> 
> Tom Cloud <cloud at peaches.ph.utexas.edu>

Usually when the sensors start to deteriorate, you can tell by the shape 
of the signal.  What used to look like a strong toggle (almost like a 
switch), becomes slower, eventhough the sensor reaches the high voltage. 
 This doesn't necessarily mean the sensor is a waste.  The 
manufacturers generally leave a margine of error for sensor response 
time in their transport delay calculations (transport delay is the 
amount of time it takes the fuel to go from the tip of the injector to 
the O2 sensor).

On a closed loop system, if you notice that the sensor is not reaching 
.8 to .9 volts, you should probably replace the sensor.  The same is 
true for the low end.  The toggle should go down to about .1 to .15 
volts.

Best Regards, Mazda