Q45 Oxygen Sensor Replacement

[mxr662]

So I spent and hour or so trying to remove my O2 sensors only to give up and put the 3 plastic engine trim pieces that were left off from the plenum R+R. (they were left off to better check for leaks.)

After getting done discovered that I was trying to remove the hex part of the exhaust manifold that the O2 sensor screws into and not the O2 sensor its self.

Now my car is slow to start. Trusty OBD scantech shows a code 11 (must have dislodged the wiring to the CAS while installing the engine trim piece.

http://q45.org/gallery/d/5365-1/02sensor.JPG

The other code that keeps popping up is 53. You can see on the screenshot below that both 02 sensors look ok but at times at 2000 rpm the left one stops going from high to low. (did not get a picture of that.

So tomorrow I'll get the 7/8 crows foot and O2 sensor wrench.

Andy http://q45.org/gallery/d/7984-2/02scope.bmp

[3Q Jay]

Andy-

the 7/8 crowfoot is the key. on the PS, it is a straight shot down from the top with long extensions. PS is pretty easy imho.DS is easier with plenum off (that is how i did mine), but probably still accessible from the top with plenum on. I suggest this is a job you commit to and then stick it out. what i mean is: use PB blaster liberally and let soak overnight--note that this in and of itself may pretty much ruin the old sensor heads ithink it did on mine as i soaked it and then drove and then suddenly started getting O2 codes where none before. i also mean that you can once committed literally chisel off the old backshell and go at it with a 6 pt 7/8 socket (did not have to on Q, but have done this before).

she will smoke like a train while the PB burns off.

[3Q Jay]

forgot to mention--harbor freight sells the crowfoot set incl 7/8 for like 15$.

[maxnix]

That's got to be a 22mm or 21mm wrench. Why risk rounding?

[elwesso]

No its actually 7/8, all o2 sensors are 7/8 regardless of make or model, these are NOT metric. Besides, when the sizes are that big it usually isnt as big of a deal.. Meaning you could substitute a 1inch socket for a 26mm bolt and itd be fine...

Anyway, the o2 sensors are one of those learning curve jobs... The drivers side is easy with an o2 sensor socket, and the passenger side is easy with the crows foot. I dont think you can do it any other way, i dont think you could use a crows foot on the drivers side (havent tried it) and I know you cant use an o2 sensor wrench on the passenger side...

I like to start the car and get it warm prior to removal, but let it cool off a while so its not hot, just warm and i think it makes them come out a little easier.

[mxr662]

After getting the tools together the job was real easy. On 1990-1993 this would take around an hour not including time for PB Blaster to soak in. I did this by myself but it would be much easier with 2 people.

The 02 sensor socket, $17 from local discount auto parts store, was for a 1/2 inch drive ratchet. I found a 1/2 to 3/8 drive adapter which made the job much easier. A 3/8 drive O2 sensor socket would be much better and eliminate the 1/2 to 3/8 drive adapter. I used black tape to hold the extensions together.

This is what I used on the drivers side. O2 socket >> 1/2 to 3/8 adapter >> 3/8 extensions.

Assemble the socket, adapter, and 2 extensions. Leave the ratchet off. Slide it up from the bottom towards the back of the IAC. Slide the socket up above the O2 sensor and the down on to the sensor.

Remove the cruise control throttle cable from the clip behind the middle of the plenum. That is where the extention should show up.

On the passenger side just slide the extensions down from the top with a 3/8 swivel attached to the 3/8 to 1/2 adapter.

Modified by mxr662 at 10:38 PM 12/21/2007

Modified by mxr662 at 10:39 PM 12/21/2007
Modified by mxr662 at 10:40 PM 12/21/2007