2006 US-Spec 3.0 Wagon here.
I was just wondering if anyone knew of the easiest way to go about replacing the oil pressure sensor? Searched around on the forum, but the only threads I found were either for the S-Type or a couple of unanswered posts for the X-Type. Looks like you may have to remove the AC compressor and lines entirely? If that's the case, that may be a problem we ignore for the moment because I'm not risking messing up my AC in the Summer 😆

Oil light comes on once the vehicle is up to temp below ~650rpms. Does this at the same rpm and temp conditions regardless of oil weight/viscosity (trust me, I was worried to death and changed the oil 3 times w/ a different filter each time to rule it out). Mechanical gauge seems to indicate fine pressure, so I'm assuming it's just the switch, because the symptoms seem to match exactly what has happened to several S-Type owners.

Edit: Actually thinking about it, my nav screen sometimes boot loops when this occurs, possible grounding issue? My neg battery cable is clean and looks good, any idea where I might be able to locate the main engine earth strap to give it a good clean?

 

I have an update to this, for anyone who needs to do their sensor in the future:

Here is the workshop manual:

Now, as you may or may not have already figured out, the workshop manual is lying.

The "official" procedure from the very very few other threads I've found is that the sensor is 100% impossible to remove without removal of the AC Compressor first. And to remove the AC Compressor, you need to remove the lines (from what I've read). Very big PITA job.

Now, through trial and error, I can confirm it's 100% possible to do the sensor without removal of the AC, you just need the right combination of tools:


First things first, you're gonna want to go to your nearest Harbor Freight and grab two packages of extensions if you don't already have the correct needed ones around. I ended up buying the 3-Pc 3/8 in. Drive Impact Wobble Socket Extension Set (SKU 67065). I also grabbed the non-wobble 4pc extension set (SKUs 67926, 2762). The non-wobble one might be optional, but if you don't have other extensions sitting around, you'll need it (or you might be able to use 2 packs of the wobble extensions, not sure, both was the combo that worked for me). If you haven't already attempted this, you're essentially working with your hand in a slot between the oil filter housing and back of the AC Compressor.

You're also going to need the Cal-Van 90-Degree Gearless Angle Drive Extension. This is not optional. I tried for 2 weekends to do it without this before a friend reminded me they existed. It feels possible to do it without it, but I couldn't find the right combination of extensions and small-head 3/8 ratchet (Air Ratchet came close but mine didn't have enough breakaway torque to undo the sensor). You can get this adapter at any Advance Auto Parts (or maybe other auto parts stores) for ~$12-15

If you haven't already removed the oil filter and connector from the sensor, do so now. Mine had the clip oriented on top of the sensor (thanks whoever assembled it), and my sausage fingers couldn't get enough downward pressure on the connector where it sat, so I ended up using the longest flathead screwdriver I had, using a bolt on the back of the AC Compressor as a leverage point, and using it to put pressure on the bottom of the connector (using the pivot point to push the connector towards the radiator).... The connector should flex enough that it'll pop past the clip and come right off.

Now, once you're removed the connector, take that long screwdriver, break the back off of the old sensor. It's the only way I found you're able to fully seat a socket onto it (hence not using a deep well in the photo above)... With the plastic there, you can slip a deep well socket over the sensor, but the socket is too long to allow you to put an extension on it without it pressing against the back of the alternator and not fully seating on the sensor (fought with this for a few hours)

Now, take a regular (short) 21MM/ 13/16" 6-point socket, and assemble that contraption in the photo above. Assuming you're doing this in your driveway like me, you'll need to be laying on your back, with your head pointing towards the driver's front wheel and your right arm/shoulder under the car. Feed the whole contraption up in there, socket first, use your right hand (probably pinky and ring finger) to guide the socket onto the oil sensor. You'll need to use your left hand to support and lift the ratchet on the back side of the contraption. Once you're positive you've got it all lined up, you should be able to remove it... Mine was very stubborn and there was a moment I was waiting for the socket to jump and round it off from the force I had put on it. Word of note: If yours is also very stuck, you can probably use an impact to help, just be aware that the 90-Degree adapter isn't impact rated and gets rather warm very quickly... so do it in short bursts if you have to, or go for it and be willing to sacrifice the $15 adapter.

You should now have the sensor out by this point in reading.

Now you'll need another tool (or two) from Harbor Freight:


The 3/8 in. Drive T-Bar With Flexible Ratchet (SKU 57175, 98484) and a 13/16 Spark Plug socket. This was the combo I found that worked. Theoretically you might be able to do this with a regular 13/16 or 21mm socket, but it would need to be ~2.5" long. The spark plug socket is almost exactly 2.5" long, the only other deep 21MM socket I had was 3.25" long and it's 100% too long to fit in there.

Now, take the sensor, put it up in there and thread it in by hand.... you can use your pinky and ring finger to roughly push it into the hole, your thumb and middle or index finger should have enough room to spin it clockwise enough for the threads to engage. Now once you've got that taken care of, thread it in as much as you can with your fingers.

Put the 13/16" spark plug on the T-Handle tool as shown above, feed it up in there. You should be able to get the socket most of the way onto the sensor before it hits the alternator. Now you'll need to just play around with the angle on the T-Bar tool to get it to slip past the alternator. I found that having the body of the tool as close to the cat as possible allowed it to slip past.

Once you've got past the alternator, I used my right hand to feel and make sure that the tool was completely on the new sensor. There's enough room between one of the hoses under there and the cat to give you enough arc swing for the ratchet to click once. Keep doing this and eventually the sensor will be tightened.

Photo of what you should be looking at:



Note that if the socket is not fully seated on the sensor, it'll be pretty obvious vs when it is fully seated. You move the tool back and forth one click at a time and eventually the sensor will be tightened.

Reinstall the connector, Took me a few minutes since you just have to do it with two fingers and by feel.

Reinstall oil filter, job done.

If I needed to do the sensor, and for some reason I had the alternator out, that would be the time to do it. The Alternator limits what tools you can get in there and is what held up a lot of progress while I was figuring this out. The AC Compressor really isn't the issue at all, it just makes it hard to get your hand in there, but you're still able to do it, and I've got pretty large hands... should be considerably easier if you're got smaller hands than me

 

Can I give you a hug?! Literally everything you just said, leading up to your solution, has been my life dealing with this headache. Not gonna say I never thought to break off the plastic, just too afraid to do it without the right combination of tools, and end up stuck. My light blinks intermittently and at complete random. Could go for weeks. I’ve changed the oil 3 times, bought 5 different tool and covered every 4 letter word in the book trying to get this damn thing out. This post is gold! Can you imagine replacing the oil temp sensor right below it?

 

Glad I was able to help, good luck!

It took me weeks to get it done, until I finally had the right combination of tools. Once I got all the tools, I had the sensor off in.... 10 minutes? I felt on top of the world after fighting it for literal weeks.

I couldn't find any other info or record of anyone having done it with the AC Compressor and Alternator in the car.... So I figured I'd better upload the process to help anyone in the future.

 

oh man, good job. Well done for persevering and really well done on the write up.

I hope never to have to do this - but now know it can be.

 

Kudus to you BuclkeSpring.
Certainly, great advice on this Engerineering nightmare. I am having flickering oil lights and had no clue where the oil pressure sensor is located.
I will now take stock of the necessary tools combination and venture into the work