Oil Pressure Switch / Sensor replacement notes/tutorial

I just changed the oil pressure sensor / switch located on the back side of my block. (2.3T B235R, 4 cylinder). It is quite common that this sensor leaks and it's a cheap part ($20). Mine started leaking at 134K miles. At first I thought my A/C compressor was leaking, because the oil spot on the driveway shows up just below the A/C compressor, but not so, it was this sensor. Below is a photo of what the old sensor looks like, covered in oil. I first removed my Starter, which is really easy. The starter is tiny & lightweight, kind of fits in the palm of your hand and comes out easily through the bottom. The top bolt that holds the starter on is kind of buried, so you'll have to feel around blind to find the bolt from the top. I had my car on jack stands and was still able to remove the starter top bolt from the top. I used the Hayes manual for instructions as to removing the starter. I removed the intake manifold, "stay" rod, only two bolts. A little oil will drain out of the hole when the old sensor is removed, but it's not a big deal.

Attachment 15824

Below is what the new sensor / switch looks like, notice the large crush washer near the threads, it's an odd, "U" shaped washer. Don't worry if your wrench hits the black plastic cap and it moves or pops off, just push it back on, it's not designed to be a seal, just a protective cap to protect the electrical contact:

Attachment 15825

Here's the critical bit of information that I couldn't find anywhere in any tutorial, online or otherwise. If I were to do this job again, I would not proceed without having this wrench, it's a 15/16, offset box end wrench that has been cut down with a 3" handle. Fits the oil pressure sensor perfectly:

Attachment 15826

I was lucky when I did this job because I was using a 24mm full size open end wrench to try to tighten down the oil pressure sensor, (tight enough to seal the crush washer) and it wasn't working, the space is too tight for a full size wrench and an open end wrench slips off the bolt head. Fortunately, my friend stopped by, happened to have the 15/16 box end wrench and offered to cut it down, I lucked out. You need to apply quite a bit of torque to the sensor bolt to actually seal the crush washer.

Attachment 15827

The final image shows the new sensor installed. Now I'm all sealed up again and no more annoying oil leaks. Plus, since I had to remove the original starter, I decided to swap in a rebuilt Bosch starter, (only $85), even though you almost never hear of Saab starters failing. My rule of thumb is that if I can get to a part in the process of getting to something else, and if that part can be swapped with a new or rebuilt, I just swap it out, broken or not. In this case, I was blown away with the new starter, it spins much, much faster the old starter with 134K miles on it.


I hope this info helps someone out there. I wish I had this info, especially about the wrench prior to doing this job, it would have made for a much easier job.

I moved this the tutorials forum so it is easy to find in the future. Great write-up, thanks for your service to the Saab community. :thumbsup:

i recently replaced the oil sensor and now i'm having oil stains on the floor! my guess is it was not tigthen enough. will have to send it back to the shop where i got it done. if i had found this thread earlier i would've paid more attention when he fixed it on.

update on my adventure, the oil stains were actually a broken return check valve to the throttle body, which was pressurizing the cam cover, and everything else when the turbo kicked in. that was fixed.

the oil pressure sender was leaking slightly as the stains were there (the area was cleaned after installation), but the washer was already crushed. just had to tighten it a little bit more and after a test run didn't seem to be leaking anymore

You take Impressive photos Photousa! :)

Quote:

---

Originally Posted by ScientificHeart

You take Impressive photos Photousa! :)

---

Thanks Katherine, just trying to give a little back to those in this community who have helped me through so many repairs :)

Hi - I've searched a ton for oil pressure sensor replacement on the 9-5. However, each and every thread seems to be for the 4 cyl.

If anyone with a 6 cyl needs to do this, thought I'd type out the simple steps as it's seemingly easier than the 4 cyl. Not that you'd need it necessarily, but might encourage you to just get it done as it's so simple.
V6 Oil Pressure Switch Replacement Procedure:

1. Jack up passenger front side of the car, get it on a jack stand.
2. Remove passenger wheel
   
3. Remove plastic wheel well shield (or at least take out enough of the screws to move it to the side)
4. R&R oil pressure sensor (which sits just below the drive belt pulley)

1. ​Disconnected the wiring connector and used a 24mm (the sensor I removed and the one I put in were both Saab OE) deep impact socket and ratchet to R&R.
2. When installing the new sensor, remember to zip tie the wiring to the oil pressure sensor "housing" so it doesn't get caught up in the moving parts like the belt/pulleys.
3. Didn't have any torque specs, so did it a little tighter than the oil drain plug - hand tight, then another 1/3 turn.
4. Reconnect the wiring connector

​
Put it all back together.

I thought at first I could get it from up top, but the space is just too tight to work. Tried to reach down between the drive belt/pulleys and the AC lines, but decided to do it the way described above.

BTW, you might wonder why am I was looking to replace this. I noticed some oil stains in the street where I park it that appear to be on the passenger side of the engine. I looked down past the belt/pulleys to see the oil pressure sensor and saw what seemed like fresh oil. I reached down there and confirmed oil on the sensor - could be leaking from many other places, but thought I'd start here. Once I disconnected the wiring connector, oil started to leak out of the electrical connector on the housing.

But really why I want to change it is that after the car was good and warmed up (again, the 6 cyl, not the 4 cyl - the 6 cyl doesn't have the sludge issue right? Please let me know if I'm wrong) and you idle at a stoplight, the warning light chimes and the oil light comes on. This goes away when you load the engine. Figured I might as well start with the leaking oil pressure sensor and hope that solves both issues (warning light/chime and oil on the street).

Another factor that might contribute to low oil pressure is the recent oil change. Not exactly sure if the P.O. used Mobil 1 5w-30, but I did and the warning lights/chime started happening about a week after I put in Mobil 1 5w30 and a Mobil 1 filter.

Awesome write up. Looks pretty straight forward' simple.
My initial issue is figuring out which switch it is i need. Best answer, i know, is just pull the starter off and see.
But, all of the auto parts sites show two completely different units with the same name. One with the wire like yours, and one with just a single plug on the rear of the threaded portion. How do i figure out which one my model needs?

2000 9-3 2.0t

Ok I replaced the sensor today. Thanks for the writeup and photos. About 2-1/2hrs from the bottom at a leisurely pace, it looked pretty much impossible from the top. I did spend some time scoping out the job and making sure I had all the tools and reading the forums before taking it on. It was much easier than I thought, the hardest part being the fidgeting around with the red connector for the sensor wire with one hand and the zip tie as well. The top bolt(18mm), from the top, for the starter came off quite easily, I used a 3/4" pipe over my socket wrench to use some leverage. Note this bolt does double duty and also connects the transmission to the engine. So at first I was not sure I had the right bolt for the starter, but I did. The bottom16mm nut(for starter) also came off easily. The old sensor comes off with a standard 24mm socket, cutting off the wire and removing the plastic cover on it. Deep socket is of course better. I think this next bit was the most important for me - I had got a original Saab sensor but that has a 24mm head, like the one removed. So unless you have a special socket you'd have to cut off off a 24mm box wrench to fit in that tight space as mentioned in the original post. Having read the forums, I realized an aftermarket sensor(22mm head) would be better as you can use a oxygen sensor socket to fit it easily - and this worked very nicely. These are some really good instructions I found - FixMySaab: 9-5 Oil Pan - Introduction.