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Replacing oxygen / O2 Sensors complete instructions

Jimmythegreek

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Jul 10, 2015
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Australia
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VZ Wagon
My car is a 08/2005 VZ Commodore. Firstly which sensors to buy because there are so many choices, I have the 4 wire ones one black one grey two white. I have no affiliation with the company of my choice, after a lot of research I bought the Oxygen Lambda Sensor AFI OXY1263 for $133 for both with free express delivery off eBay. The reason is it is an established proper bricks and mortar business in Australia and has 12 month warranty. They look the closest to the factory sensors without paying crazy original GMH prices. They made a huge difference in power and petrol economy after fitting.

Now how to fit them, make sure you warm up the exhaust before starting the job. From under the bonnet unclip the passenger side sensor, if it is stubborn push the clip in by holding both ends then push the release tab down and separate (because you can’t see the clip you are undoing a simple trick is to look at the new clip and it helps you have a mental picture of the clip you are undoing makes it a lot easier for me).

Jack up the front and USE STANDS (Please don’t ever trust your jack without stands) then from under the car and using a 7/8 open ended, unscrew the passenger side sensor. Really easy to do with heaps of access, put on the new sensor do not clip it in until you have screwed in the new sensor all the way. Do not add anything to the threads DO NOT SPRAY THE SENSOR WITH CRC TO MAKE IT EASIER TO SCREW IN you will ruin the sensor. That is the passenger side done very easy (will clip together a bit later on).

Now the hard one drivers side, drop the transmission cross member. Support the cross member with your jack so you take the weight off the bolts you are unscrewing (you might shear the last part of the threads if under load). Undo both exhausts near the transmission cross member, use CRC to make it easier to take off the exhaust bolts, your exhaust gaskets will be a bit rough, if you don’t damage them you can reuse them. Once you have done that drop the transmission off the jack and it should have dropped enough to give you fair access to the sensor clip on top / drivers side of the transmission.

Now to unclip that sensor position yourself in the right direction, what I found easiest was to lie with my head at the driver’s door my legs towards the passenger door and I used my left arm over the rear of the transmission until I was able to reach the clip side secured on the transmission, I used my right arm on the side with the release tab on the clip, again if it is stubborn push the clip together then push down the release tab and separate. Once the clip is separated now unscrew the sensor.

There is not a lot of room to unscrew the driver’s side sensor because of the steering. I found by doing a little bit of unscrewing and flipping the 7/8 you can work it off. Unscrew a bit on the engine side of the exhaust, then swap over to the chassis side of the exhaust and so on back and forth until loose enough to undo by hand. Once you get it off then screw on the new sensor before plugging it in to the clip. Tighten screw in by hand as much as possible and again using the 7/8 in the above method to tighten properly. Now clip on the sensor clip, again position your body in the right direction using the same method when uncliping, make sure you hear the clip lock in.

Now use your jack to jack up the transmission cross member do not jack all the way up leave a small amount of space between the cross member and the body of the car to be able to have a bit of play to fit the bolts. Before fitting the cross member bolts while the cross member is jacked up bolt the exhausts together, put the old gaskets and again use CRC to make them go on a bit easier if you like. My gaskets were pretty worn and I didn’t use any gasket goo, no exhaust leak could be heard when running. Screw the cross member bolts, do not fully tighten the bolts until they are all just about done up try your best to seat the bolts in the original positions and tighten them all up, reason for this is so you get no vibrations from the tail shaft.

Drop the car off the stands and jack and then from the top of the car clip in the passenger side sensor again make sure you hear the clip lock in. Start it up and see how you went, my car did not automatically get rid of the drive train error code, I had to go to my mates garage and cleared the code, it was perfect after that. Shop around and find someone who has the computer to reset the codes, everyone has a computer from auto elecs to mechanics to wrecking yards to dealers, try to find the cheapest.

Also note if you are getting a code telling you to service vehicle soon (SVS) this has nothing to do with a service. It is your oil pressure switch; there is no way to clear that until you replace it. When done you do not have to have code reset it will clear its self after a couple of starts. Again I bought it off eBay, cost $30 free postage there are heaps of choices, I bought one listed as genuine Holden part, it matched the original part exactly in looks, was made in Mexico like the original, just that the part numbers were different but still looked exactly the same.

The way to do a quick check if leaking (and you have no error code) is to swipe your fingers under the oil pressure switch and see if there is a bit of oil there, if there is needs replacing. When I replaced mine it had oil in the actual plug connection / pin area, I blew it out with compressed air before plugging it back in Good luck I hope this helps out some people out.
 
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