Re: Oxygen Sensors when to change??

"The Henchman" <dontsellmestuff@[EMAIL PROTECTED]
> wrote in message
news:3eWfj.174781$uv7.82120@[EMAIL PROTECTED]
>
> "maxpower" <damnnickname@[EMAIL PROTECTED]
> wrote in message
> news:sLOdncFZnuF-jB3anZ2dnUVZ_oGjnZ2d@[EMAIL PROTECTED]
> >
> >
> > Not true. The first purpose of the downstream 02 sensor is to  measure
cat
> > efficiency. The second function  is downstream fuel control. This
function
> > adjusts the upstream 02  goal  voltage within the range of operation
of
> > the
> > upstream sensor. The upstream goal voltage is used to ensure long cat
life
> > by allowing the pcm to control the amount of air and fuel that is
supplied
> > to the cat. If the downstream 02 sensor switch point is at a  low
voltage
> > the Pcm will adjust the upstream 02 goal voltage to reduce  high 02
> > content
> > by . If the downstream 02 sensor  switch points stays  high, the
upstream
> > 02 sensor goal  voltage will change and  allow a low 02 content.
> >
> > Glenn Beasley
> > Chrysler Tech
>
> I don't get it.  There are two downstream sensors are there not?  Does
the
> downstream sensor on the drivers side control the bank 1 sensor on the
> exhaust manifold and the passenger side sesnor talk to the bank 2 sensor
on
> the manifold?  Is there a map as to how these sensors talk to each
other.
> One of them are giving me a low voltage error thants all I know.  All
cars
I
> had before now I would change the sensors at 100 K km (60 000 mile
odometer)
> read.
>
> I got to take this car intot he delaer for a 100 K km tune-up.    Should
i
> be spending the $200 required to change all 4 sensors?   is this a
normal
> thing?  What does low voltage from an O2 sensor mea?  What is upstream
and
> what is downstream?
>
> Thanks for all the help and have a great weekend!
>
>
There are (4) 02 sensors on that vehicle. 2  upstream sensors (located
before the catalytic converters),   one on the left side and one on the
right side. And 2 downstream sensors one on the left and one on the right
side just past the catalytic converter. The  purpose of the up stream
sensor
is to maintain the proper air fuel mixture. And the downstream sensors are
used to make sure the catalytic converters are working. When looking at a
scan tool to determine which sensor is where. 1/1 is the upstream sensor
on
the number cylinder side, 1/2 is the downstream 02 sensor on the #1 cyl
side. 2/1 is the upstream sensor on the other head. 2/2 is the downstream
sensor on the same head as the 2/1.
The p0137 fault is referring to the downstream 02 sensor on the back head
past the catalytic converter (it is the downstream sensor rear head)
The monitored  set condition is (cold start engine, coolant below 98
degrees
and ambient temp with 20 degrees of engine temp The fault code will set 
if
the 02 signal volts is below .059 volts for 3 seconds after  starting the
engine.
The  sensor is shorted to ground either at the sensor or the wire going to
the PAM from the sensor is shorted. Best bet would be replacing the (1/2)
02 sensor only.


Glenn Beasley
Chrysler Tech