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  • SN95 4.6L Mustang Tech

O2 sensor orientation

  • Thread starter Thread starter Slowstang96
  • Start date Start date Nov 9, 2006

Slowstang96

Founding Member
May 31, 2002
92
0
0
Tampa
Nov 9, 2006
#1
  • Nov 9, 2006
  • #1
Stupid question, does the placement of O2 sensors matter (front to back?) When I put my prochamber on, I laid them out in the correct order, but some neighborhood kids came by and one of them moved them while I was under the car. I replaced them by color, but the front driver sensor doesn't reach. I just taped it up until I could get an extension. I thought only 04's had length issues, I've got an 03. The car could be running worse because of it, but I can't tell because of the exhaust leak (whole nother story.) So is it possible that I just got them crossed? If not, cant I just splice in some wire to extend (less than an inch needed) any idea what guage wire?
 

jstreet0204

Active Member
Jun 26, 2003
939
0
36
Winston Salem, NC
Nov 9, 2006
#2
  • Nov 9, 2006
  • #2
Other than the harness, the o2's are exactly the same. Front, rear, left, right, they are all the exact same 4 wire o2 sensor. That is why you can buy universal o2 sensors that you can cut the harness to the length you need.
 

sgarlic

Founding Member
Apr 21, 2001
3,085
1
56
Nov 10, 2006
#3
  • Nov 10, 2006
  • #3
I would switch the correct one back (the one that reaches.)

I have read lots and lots about sensors, and I seem to recall Randy mentioning to not switch them.

I would also think that the PCM compensates for wear differences in them, so it would apply whatever it has learned to whatever sensor is in there, unless you reset it.
 

RandyStinchcomb

New Member
May 25, 2005
1,159
3
0
Randallstown, Md
Nov 10, 2006
#4
  • Nov 10, 2006
  • #4
sgarlic said:
I would switch the correct one back (the one that reaches.)

I have read lots and lots about sensors, and I seem to recall Randy mentioning to not switch them.

I would also think that the PCM compensates for wear differences in them, so it would apply whatever it has learned to whatever sensor is in there, unless you reset it.
Click to expand...



yes that is correct, O2 sensos (ahead of the cats) and O2 monitors (aft of the cats) should NEVER be swapped around. be extra carefull if you do the cut n' splice as any mistake in soldering will effect the O2's performance.
 

jstreet0204

Active Member
Jun 26, 2003
939
0
36
Winston Salem, NC
Nov 10, 2006
#5
  • Nov 10, 2006
  • #5
RandyStinchcomb said:
yes that is correct, O2 sensos (ahead of the cats) and O2 monitors (aft of the cats) should NEVER be swapped around. be extra carefull if you do the cut n' splice as any mistake in soldering will effect the O2's performance.
Click to expand...

I disagreed with you the last time you posted this and I'll dissagree with you again. The o2's themselves are the same. The ONLY thing that differs is the length of the harness. I have switched out my o2's front to rear, and they function exactly the same and used wideband data along with datalogs of the o2's to verify. Unless someone screws up the wiring they will not have a problem.
 

RandyStinchcomb

New Member
May 25, 2005
1,159
3
0
Randallstown, Md
Nov 10, 2006
#6
  • Nov 10, 2006
  • #6
jstreet0204 said:
I disagreed with you the last time you posted this and I'll dissagree with you again. The o2's themselves are the same. The ONLY thing that differs is the length of the harness. I have switched out my o2's front to rear, and they function exactly the same and used wideband data along with datalogs of the o2's to verify. Unless someone screws up the wiring they will not have a problem.
Click to expand...



ok, well you do it your way(which is wrong) and we'll leave it at that
 

jstreet0204

Active Member
Jun 26, 2003
939
0
36
Winston Salem, NC
Nov 10, 2006
#7
  • Nov 10, 2006
  • #7
RandyStinchcomb said:
ok, well you do it your way(which is wrong) and we'll leave it at that
Click to expand...

Just clearning up the facts so people can make educated choices on thier own.

To make it little clearer as to why the front an rear o2's are electronically the same you should understand how the cats are monitored. They are monitored by checking the difference between the switch rates of the front and rear o2 sensors. If the switch rate of the downstream O2 sensor (which normally switches pretty slowly due to the consistent gases leaving the cat converter) starts to catch up with the switch rate of the upstream O2 sensor, a "catalyst efficiency monitor failure" code is set. Therefore they have to operate the same way in order to be able to compare the switch rates.
 
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