ugh so it's not advised to do this? I tried to put the stud in without dropping the Y pipe and that was not going to happen.. I think the stud and nut was like $25 or $30 something.

 

Nothing else has come out but I expect a stud to back out while undoing the header

 

For a whole set maybe. Find your local "Fastenal" or similar fastener/hardware store and take them the old stud. They can match it up with a new bolt or stud and get some pinch nuts to go along with it for only a few $$ usually. Use lock washers if you put bolts in instead of studs.

Just replaced the oxygen sensor on my 99 OBW. I couldn't use the standard O2 socket, that looks like a sparkplug wrench with the side cut open. Someone recommended using a 22MM crows foot wrench, but I couldn't get a good grip with that.

 

Out of frustration, I went shopping for a better oxygen sensor wrench. I found one at O'Reillys Auto Parts store, but prolly available elsewhere. I bought a tool manufactured by Performance Tool Co. They call their drive socket an Offset Oxygen Sensor Wrench. That tool worked perfectly within the small space confines allotted by Subaru to do your work. I highly recommend the tool. Cost was $10.

 

I bought a Bosch O2 sensor from Amazon for $61 that included free shipping. The Bosch unit works just fine.

 

It helps to use plastic drive up ramps, and chocks at the rear wheels, to get under the car. Recommend using PB Blaster a day or two in advance, plus warming up the motor, to get the old sensor out.

I'm wondering why you were unable to use that type of oxygen sensor socket?

I'm wondering why you were unable to use that type of oxygen sensor socket?

probably lack of space - not a lot of room between the the top of the sensor & the body of the car.

 

I used a 22mm offset boxend wrench to change mine - maybe not the ideal solution, but it worked, had just enough offset to reach down & in to get a good grip on the sensor and it didnt cost me a penny as we already had the offset wrenches.

wait are you talking about the front 02 sensor or the rear?

 

I have a lot of room on mine maybe stuff changed on the later models.

only had one on mine - 1990 - not a lot of space to get to it.

Ah I understand now

probably lack of space - not a lot of room between the the top of the sensor & the body of the car.

 

I used a 22mm offset boxend wrench to change mine - maybe not the ideal solution, but it worked, had just enough offset to reach down & in to get a good grip on the sensor and it didnt cost me a penny as we already had the offset wrenches.

 

I read your earlier post about using 22 mm offset so, I went shopping for one at auto parts stores, but couldn't find one. All they sold were long straight 22 MM wrenches.

we got an entire set of metric offsets at good ol harbor freight - have proven useful more than once. also have a set of ASE offsets, a set each of stubbies, and a set each of S-shaped ones - all from HF.

trying to buy just one - yeah, good luck.

we got an entire set of metric offsets at good ol harbor freight - have proven useful more than once. also have a set of ASE offsets, a set each of stubbies, and a set each of S-shaped ones - all from HF.

trying to buy just one - yeah, good luck.

 

 

Thanks, good info!.

Thanks, good info!.

 

Welcome - good luck!

 

just wished i had an S shaped offset the other day, tho! would have been VERY useful!

Got sided tracked but it's bad now I estimate around 11-13 MPG now I'm going to order the sensor tomorrow I've got some kroil so word has it, that it works better then PB blaster.

I recently installed a Bosch 02 sensor. It works just fine.

When you did your did you replace it because you noticed hesitation or did you get a CEL? I get hesitation after say driving for like 3 min after warming up the car after sitting for like 4 hours or so.

 

I wonder why some trigger the CEL sooner then later and some never at all until it's like undriveable.

 

Hopefully no issues when removing it.

I was messing around under the hood on Saturday and I noticed I was revving my car but the EGR was not opening which If I'm right it should start to open around 3K?

 

I'm scared to push it open since when I had my 98 Forester it got stuck open and made the car a *************** to start..

When you did your did you replace it because you noticed hesitation or did you get a CEL? I get hesitation after say driving for like 3 min after warming up the car after sitting for like 4 hours or so.

 

I wonder why some trigger the CEL sooner then later and some never at all until it's like undriveable.

 

Hopefully no issues when removing it.

 

My bad 02 sensor triggered a CEL. I had a parts store read the code. They told me it was a bad sensor. The toughest problem is to get the existing 02 sensor loose. It will be on super tight. My sensor removal socket loaded the drive at the end of the sensor. This won't work on a Subie, as there is no room to attach the drive handle. So, I got lucky at an auto parts store, and found an 02 sensor removal socket with an offset where the drive handle attaches. I used a short extension between the socket and the drive handle. When removing the sensor, run motor for a short period of time to warm up the exhaust pipe. I slid a small metal pipe over the drive handle, which lengthened the drive handle for more leverage. I also drove my OBW front wheels up on ramps, so there was enough room under the car to work. I applied the hand brake, and chocked the rear wheels to prevent the car from moving.

Yeah I'm going to go get an offset socket Friday between the koil heat and muscle hopefully it wont be a problem.

Yeah I'm going to go get an offset socket Friday between the koil heat and muscle hopefully it wont be a problem.

 

Just remember to slide a length of pipe over your existing drive or breaker bar handle. The added length gives added leverage makes all the difference in getting that tight 02 sensor to break loose. I will guarantee you, it will be TIGHT!!

 

I found it easier to tighten up the new 02 sensor with an open end wrench.

it's something like 22 mm not sure what the size would be in SAE since I don't have any metric open end wrenches but I don't think I have it in standard as well.

it's something like 22 mm not sure what the size would be in SAE since I don't have any metric open end wrenches but I don't think I have it in standard as well.

 

The 02 sensor is the same size base as the old style (large base) spark plugs of long ago, whatever size that is. I am thinking either 7/8" or 13/16" in SAE, but I might be wrong. However, it is a common size in SAE, so I don't think you will have trouble finding an open end SAE size wrench in your tool box that will fit. I do remember that the size needed is an exact same size in both SAE and metric. It is the only time, that I have ever found an SAE size to match up exactly with a metric size.

The 02 sensor is the same size base as the old style (large base) spark plugs of long ago, whatever size that is. I am thinking either 7/8" or 13/16" in SAE, but I might be wrong. However, it is a common size in SAE, so I don't think you will have trouble finding an open end SAE size wrench in your tool box that will fit. I do remember that the size needed is an exact same size in both SAE and metric. It is the only time, that I have ever found an SAE size to match up exactly with a metric size.

 

 

Yeah I will check the tool box tomorrow I gotta have something in this stuffed box

I have done a few of these in various makes. Had a problem only once (threads pulled out of the cat). The sensor is shot so just cut the wire! Soak overnight in penetrating oil . Make sure you have enough room to get a socket on it, if not remove a few rubber hangers and lower the rear of the exhaust. Warm up the car. use a six point socket( I cringe every time i hear someone say just buy a cheap tool) at the very least use a craftsman. It should come right off!! Afterward, go inside and put some ice on the burns your bound to get from the hot exhaust pipe.

Ah well this sucks thought I would be doing it over the weekend however rockauto shipped my whole order from CA so it wont be here until the 20th

 

Hopefully nothing stupid like the threads will come out.

I did the rear on my 97 Outback like last week..soaked it for like 2 days and rented a O2 sensor socket set from advance for like $30 (full refund upon returning it).though i had a couple people say to use a 7/8 boxed end wrench (i figured i'd try the socket)

 

well things didn't turn out so good..snapped the threaded bung clean off the cat.. (it has happened before with the Jeep,though i got injured on that one)..ended up having to replace cat..

 

I hope you don't have the same issues..good luck.

question what was your deciding factor in replacing the rear o2 sensor since I hear it really has no effect on fuel trims.