ID the 4 wires in O2 sensor

  • Thread starter Thread starter # Fred #
  • Start date Start date
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# Fred #

Sorry not Volvo but I know you guys here have great answers. My boy yank the
wires off the O2 sensor connector by accident when he change out the
catalytic converter and looks like the color code doesn't follow through
from O2 unit to the connector to the wire harness.

So from the O2 sensor pigtail I have 4 wires: two blacks, one green and one
white. The two blacks has a reading about 10 ohms across it and the green
and white is open. I assume blacks is the heater with one 12V and the other
at ground - polarity makes on difference, right? So this left the green and
white as sensor, right? Green and white polarity makes no difference, right
also? How many ohms should be measured once I apply some heat to the sensor?
If polarity counts, how could I find out which is what?

Sorry for so many questions and thanks in advance.
 
# Fred # said:
Sorry not Volvo but I know you guys here have great answers. My boy yank
the wires off the O2 sensor connector by accident when he change out the
catalytic converter and looks like the color code doesn't follow through
from O2 unit to the connector to the wire harness.

So from the O2 sensor pigtail I have 4 wires: two blacks, one green and
one white. The two blacks has a reading about 10 ohms across it and the
green and white is open. I assume blacks is the heater with one 12V and
the other at ground - polarity makes on difference, right? So this left
the green and white as sensor, right? Green and white polarity makes no
difference, right also? How many ohms should be measured once I apply some
heat to the sensor? If polarity counts, how could I find out which is
what?

Sorry for so many questions and thanks in advance.
Click to expand...

I'm sure you're right about the black wires, but the polarity is important
on the other two. The output is a DC voltage that varies between about 0.1
and 0.9 volts. My guess is that green is ground (negative) and white is the
signal lead (positive). Maybe the green wire reads low resistance to the
exhaust, or maybe the white one does?

Mike
 
# Fred # said:
Sorry not Volvo but I know you guys here have great answers. My boy yank
the wires off the O2 sensor connector by accident when he change out the
catalytic converter and looks like the color code doesn't follow through
from O2 unit to the connector to the wire harness.

So from the O2 sensor pigtail I have 4 wires: two blacks, one green and
one white. The two blacks has a reading about 10 ohms across it and the
green and white is open. I assume blacks is the heater with one 12V and
the other at ground - polarity makes on difference, right? So this left
the green and white as sensor, right? Green and white polarity makes no
difference, right also? How many ohms should be measured once I apply some
heat to the sensor? If polarity counts, how could I find out which is
what?

Sorry for so many questions and thanks in advance.
Click to expand...


Blacks - ground.
Green - Heater +12v.
White - Signal +0.1-+0.9v approx.

Tim.
 
Tim.. said:
Blacks - ground.
Green - Heater +12v.
White - Signal +0.1-+0.9v approx.

Tim.
Click to expand...

For the connector to the car I found the 12V and one ground but how to
verify which terminal is the +signal?

Also resistance lowers across the green and white terminals as heat is
applied to the sensor, so shouldn't green be signal ground? Forgot to
measure output voltage to verify polarity on the sensor.
 
# Fred # said:
Sorry not Volvo but I know you guys here have great answers. My boy yank the
wires off the O2 sensor connector by accident when he change out the
catalytic converter and looks like the color code doesn't follow through
from O2 unit to the connector to the wire harness.

So from the O2 sensor pigtail I have 4 wires: two blacks, one green and one
white. The two blacks has a reading about 10 ohms across it and the green
and white is open. I assume blacks is the heater with one 12V and the other
at ground - polarity makes on difference, right? So this left the green and
white as sensor, right? Green and white polarity makes no difference, right
also? How many ohms should be measured once I apply some heat to the sensor?
If polarity counts, how could I find out which is what?

Sorry for so many questions and thanks in advance.
Click to expand...

According to the instructions for a Bosch universal replacement sensor I
have handy, there are 4 possible OEM wiring colour combos (that this
universal sensor was designed to replace), your combo is "Type C"

signal wire = green
heater wires = black
signal ground = white

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)
 
According to the instructions for a Bosch universal replacement sensor I
have handy, there are 4 possible OEM wiring colour combos (that this
universal sensor was designed to replace), your combo is "Type C"

signal wire = green
heater wires = black
signal ground = white

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)
Click to expand...


Thanks Mike.

Is there a way to verify on the car connector which is signal +? If no
method is available, I'll reverse the terminals when poor mileage is
observed.
 
# Fred # said:
Thanks Mike.

Is there a way to verify on the car connector which is signal +? If no
method is available, I'll reverse the terminals when poor mileage is
observed.
Click to expand...

With the ignition on, the signal wire should have about +0.45 volts DC on it
from the ECU.

Mike
 
Michael Pardee said:
With the ignition on, the signal wire should have about +0.45 volts DC on
it from the ECU.

Mike
Click to expand...

Thanks. Car is running fine for a week, lucky guess.
 
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