oxygen o2 senser replacement in 95

[skifast]

Just replaced my oxygen sensors. In the 95, there are two. One you get to from underneath the car, and the second is below the coil pack.

The first one under the car is on the drivers side of the exhaust manifold/pipe. You can see it and reach it from under the car. I loosened the sensor with a 22mm open end wrench. The wasn't much room to work, so it took a number of time repositioning the wrench to getit loose. Then since I could not get my hands to the wire harness/plug I removed the plastic cover the is under the radiator. Actually, I removed the all of the fasteners except the ones toward the rear of the car. I pulled the plastic down and worked my arms up the sensor and the wires. Installed the new sensor and put the cover back in place. For those who don't know, the fasteners are removed by pulling the round head straight out with pliers. The pull out the rest of the fastener.

The second sensor is right below the ignition coils. I removed the cruise vacuum tank(2 10mm screw and a vacuum line), then I marked all the plug wires with colored tape(so I would know where they went when I put it back together). Then I removed the coil bracket. Two 10mm screws on the front, one on each side. Then the two 10 mm screw on the back. The two in the back are toward the center, so you have to feel around, or climb up on the engine to see them. Then unplug the four plugs, two on each side. The coil assembly lifts away. Then loo straight down where the assembly was and you wiil see the sensor. I used a O2 Sensor socket I borrowed from Autozone($15 deposit fully refundable when returned) to remove the sensor. There isn't room for a wrench, so use the socket and a couple extensions. Install the new sensor and put the car back together. If you have not replaced the PCV valve, it is a good time to do it, since it is right there. If you have replaced it make sure you push it back in, in case it came out a bit when you removed the passenger side front bolt on the coil assembly.

[algonquin]

Nice thread.

[BACK2LIFE]

nice! need some pics thought to put in the maintenance section if there isn't one there already

[scottydl]

I'm going to add this into the Maintenance sticky since we don't have another write-up on 02 sensors. To make this applicable to later Classics, as skifast said in another post:

skifast said:

If you have a 96 or later, I believe there are two additional sensors on each side of the cat. conv.

[bufo]

scottydl said:

I'm going to add this into the Maintenance sticky since we don't have another write-up on 02 sensors. To make this applicable to later Classics, as skifast said in another post:

skifast said:

If you have a 96 or later, I believe there are two additional sensors on each side of the cat. conv.

Is there a guide for replacing oxygen sensors for a 2nd gen?

[pmprogrammer]

I saw in
another post where the GM manual says to lower the engine subframe to replace the firewall-side manifold O2 sensor. Fortunately I found skifast's post and used his method instead!

I'd like to add some pictures to help out. Mine's a 96 - not sure how much of this applies to the 97 - 99 models.

Here are the tools I used for this job:


Here's the before shot. I chose to remove the silver manifold intake cover. 13mm socket fits the hold-down nuts. Removing the cover allows more freedom of movement for the bank 1 plug wires so you don't have to disconnect any of 'em, and the manifold underneath the cover makes a nice place to prop up the coil pack while you're working on the sensor.


After removing the intake manifold cover, disconnect the 4 leads (two on each side) of the coil pack. Note: No need to disconnect any of the plug wires - just the 4 harness wire leads. For each connector, gently lift the holddown tab, and lift the connector straight up. Pic shows driver's side - pass side similar.


The coil pack is held on by two hex screws, one on each side of the coil pack - use a 10mm socket to remove them. On the driver's side, lift the plug wires out of the way to get to the screw. Skifast mentioned two more hex screws in back of the coil pack - maybe a PO had neglected to put 'em back on my car.


Now carefully lift and place the coil pack onto the manifold - careful not to crimp or jam any wires or tubes/hoses.

The red circle shows the already-disconnected sensor lead. It's tight getting to this connector to unhook it, and since the plastic is brittle with age, I ended up breaking the factory plastic tie-down around the wire conduit. No worry though, zip-ties work great in their place. Once that's disconnected, on to the fun part.


Use the right tool for the job. The Sensor socket is not terribly expensive and works on most (all?) O2 sensors. Also, the swivel-extension and breaker bar make the job a bit less challenging. The cheater pipe gives you more leverage, and gets your hands away from wires & coil packs when you're breaking the sensor loose.


Here's a shot of the sensor where it lives. This picture makes it look so accessible...but it's NOT!


Here's how the breaker bar and cheater pipe look in action. Keep downward pressure on the sensor socket with one hand, while pushing the cheater pipe to loosen the sensor. When mine came loose, I thought the socket had slipped off of the sensor, but to my surprise, the sensor was loose and could be removed by hand.


Installation is basically the above steps in reverse. A couple of things to note. You might not need to use a cheater pipe in re-assembly - if you do, be careful not to break something - it adds a lot of leverage.

Don't forget the ground strap on the passenger-side of the coil pack.


And on my Aurora, the plug wires are gathered together by a clip which slides onto one of the manifold cover hold-down posts...don't forget to put that back on.


Hope this writeup helps make this job a little less daunting.

Cheers!
PM

[drail]

Thank you!!! What is the cost on the sensor for the manifold.

[sall]

see you found the thread here you go:

ACDELCO Part # AFS109 More Info {#19178958, 25312203}
SENSOR,Heated OXY(Position 1) IN EXH MANIFOLD/CROSSOVER
$75.79

That should be it.

[drail]

You a lifesaver. I wonder should I replace the other oxygen sensor on my aurora. I mean it do have 110,000 miles on it. I guess it won't hurt. I guess rockauto.com is the best place to get classic aurora parts.

[typicalconsumer]

Which sensor is considered L and which one is R?

[bobsblue95]

on a classic, the firewall side is bank 1, right side of engine.

[map79z28]

Just replaced the bank 1 o2 sensor on my '96. I kept getting the P0133 code. Few comments to the sticky above. The pics do not work. As stated in the detailed sticky, the spark plug wires do not need to be removed from the coil pack. I used the removal tool with the swivel handle. I did however, have to get under the car and use a cheater pipe to break the old sensor loose. It is tight but was able to do. It may have been easier to remove the cruise vacuum then it would be a straight shot to the sensor - if you have the straight socket - which I didn't have. Hope this helps.