[tmtalpey]

I think you need to drop the pan and take a very close look.

 

[tmtalpey]

IMO it's not the sender. Switch doesn't care about corners and slosh. VIDA doesn't either.

Again. Drop the pan. And, before a bearing runs dry.

 

[tmtalpey]

What would cause an issue like that to show up though? Especially after I dropped the pan several months ago and cleared everything out? Wouldn't this have come up pretty soon thereafter if something was wrong then?

If you suspect the oil pressure sender, you need to test. Put a gauge on the port like the VIDA procedure Facusan posted. But this is not a common failure.

Mainly I'm focused on your recent oil pan job. It's quite common that such a job dislodges an o-ring or alters the pickup tube. And you say the word "sludge".

Either one you choose to do, you need to get in there. Don't drive it in the meantime, since it happens so readily.

 

[tmtalpey]

I would not suggest a T- fitting, it can potentially change the reading, and it should be temporary!

If you insist, then put the gauge on a straight through leg, and the sensor on the 90. Don't run any extra tubing.

 

[tmtalpey]

Air, debris, you name it. It might be accurate, but you don't want guessing.

I'm not sure if there's a factory spec, but IMO on a Volvo engine (exceptionally well-made) you want to see 20+ psi at idle and double that at higher rpm. If you see 7psi on a cold engine, you are in trouble. Heck, if you see it on a hot engine, you have an issue.

 

[tmtalpey]

You may not need to remove the air box, you can access the sensor from under the car

This.

 

[tmtalpey]

Yeah, removing the airbox really doesn't help much. I marked up Facusan's photo

 

[tmtalpey]

Any reason to get the OEM sensor over something aftermarket like iPD? Will OEM last longer or are they all about the same?

You want the OEM part for this, but I bet that's exactly what iPD sells.

Test first and maybe save your money.