# Removing Wiring harness from 02 sensor ??



## fordy (Sep 13, 2003)

..........This is a 2003 Chevy dually , 8.1 big block !

.....................SAS , service engine soon came light came on so I scanned computer and it said drivers side Oxygen sensor needs replacing ! Takes a 22 mm wrench , but I can't seem too see how to UNplug the wiring harness from the sensor . I want to remove the harness before I UNscrew the sensor from it's fitting on the exhaust pipe . , thanks , fordy:shrug:


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## agmantoo (May 23, 2003)

Fordy, 
Someone that owns that specific vehicle can give you a better reply but I think the wires on most oxygen sensors are permanently affixed at the sensor itself. The plug is on the other end. Most removals/replacements will require you to use a special socket to be able to work with the wires. You can probably borrow the socket from one of the box auto stores.


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## fordy (Sep 13, 2003)

agmantoo said:


> Fordy,
> Someone that owns that specific vehicle can give you a better reply but I think the wires on most oxygen sensors are permanently affixed at the sensor itself. The plug is on the other end. Most removals/replacements will require you to use a special socket to be able to work with the wires. You can probably borrow the socket from one of the box auto stores.



.............Agman , thanks . There are several former GM mechanics that are now Compressor mechanics so I'll consult them as soon as I see them at work ! Thanks , fordy


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## clovis (May 13, 2002)

Can you use an adjustable wrench? Is there room to get one on it?


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## fordy (Sep 13, 2003)

clovis said:


> Can you use an adjustable wrench? Is there room to get one on it?


............Clove , I have plenty of room too UNscrew the sensor , the part I'm not sure about is removing the wiring harness from the sensor , Before I UNscrew it from its housing on the exhaust pipe . I was going to take a pair of channel locks and try to see if the wiring haress would simply come out . The heat is going too make removal extra hard I'm thinking so I don't want too force the removal when I have never worked on a Sensor before . , thanks , fordy


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## Wis Bang 2 (Jan 12, 2010)

GM O2 sensors have a pigtail insulated w/ woven metal to a 'weather pack' disconnect plug a few inches away. I used to change the ones on my S-10 w/ a box wrench after disconnecting the plug. O2 sensor sockets look like a deepwell socket w/ one side ground away 3/4's of the way up to let the pigtail clear. You still need to disconnect the pigtail b/4 removing the sensor.


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## foxtrapper (Dec 23, 2003)

I'd just clear the CEL and let it go. If the sensor truly is bad, you'll get repeats of the same code. I would not replace the sensor just because of a single tripping of the CEL.


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## fordy (Sep 13, 2003)

foxtrapper said:


> I'd just clear the CEL and let it go. If the sensor truly is bad, you'll get repeats of the same code. I would not replace the sensor just because of a single tripping of the CEL.



..................Appreciate the info , I'm going too attend to another small problem and then I'm going to make a couple of fast runs up too about 80 mph After I've cancelled out the code ! Then , we'll see if it keeps repeating the same code . Iy so , Then I'll purchase a new sensor . Tnanks , fordy:cowboy:


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## tamsam (May 12, 2006)

Check your air filter too. It can cause a false reading. At least I have always been told that. Good luck. Sam


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## Beeman (Dec 29, 2002)

Which O2 sensor?, that vehicle has multiple sensors. If it's setting a code it's most likely not the sensor but a condition causing it. Common code is for post catalyst O2 sensor which many times means your catalyst is ineffifcient. It can be tricked if necessary and you don't want to buy a catalytic converter.
O2 sensor will have a 3 wire connctor, follow the wire from the sensor up and you'll eventually come to it.


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## fordy (Sep 13, 2003)

Beeman said:


> Which O2 sensor?, that vehicle has multiple sensors. If it's setting a code it's most likely not the sensor but a condition causing it. Common code is for post catalyst O2 sensor which many times means your catalyst is ineffifcient. It can be tricked if necessary and you don't want to buy a catalytic converter.
> O2 sensor will have a 3 wire connctor, follow the wire from the sensor up and you'll eventually come to it.



................The code reader said it was the drivers side 02 sensor ! It is located maybe 12 to 16 inches belowthe exhaust manifold ! I was told on another website too make a couple hispeed runs up too about 85 mph , clear the code and see if it comes back on . 
..................Will it clear itself UP , or do I have to cancel it out with the code reader ? , thanks , fordy


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## cfabe (Feb 27, 2005)

If it's the one near the manifold it needs to be replaced. The one farther back on the exhaust, past the cat is just to check the emissions, but the front is is what corrects the fuel mixture.


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## Beeman (Dec 29, 2002)

fordy said:


> ................The code reader said it was the drivers side 02 sensor ! It is located maybe 12 to 16 inches belowthe exhaust manifold ! I was told on another website too make a couple hispeed runs up too about 85 mph , clear the code and see if it comes back on .
> ..................Will it clear itself UP , or do I have to cancel it out with the code reader ? , thanks , fordy


 Did it say bank 1 sensor 1 or say pre cat? Are you reading data or is this just a code reader? You will have to clear the code or meet the required drive cycles without the sensor being out of specs. Drive cycle method could actually take weeks depending on your drive lengths and style. 
Those are heated O2 sensors meaning they have voltage applied to them on startup to heat them quicker and not depend upon exhaust gas to heat them. You could possibly have a problem in that circuit. Running it hard will obviously heat it up and blow it out, the pre cat sensor that is. How much does a speeding ticket cost?


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## alleyyooper (Apr 22, 2005)

You don't need to do 85 MPH to get the sensor hot. It's RPMs that make the heat. Just leave it in low and run it at the max RPM's. A ticket here in Michigan for that kind of over speed would be near $250.00.

Most GM o2 sensor pig tails are about 6 inches long at the most. Follow the wire from the sensor to the plug in and simply pry the lock tang up a bit and unplug it There might be a gray lock pin holding the lock tang down. Simply pull it out from the upraised end rearward. . Some times they will get a bit of carbon on them so you get a reading the sensor is bad, Well it is because of the carbon but you can clean the sensor by soaking it in some sno bowl towlet cleaner.
We always used the socket with the one side cut away to remove the sensor. One on a Buick was a bear unless you took a 22MM box wrench and cut it like a line wrench so you could get it out.

 Al


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