P0521 code - gauge on dash reads 20-25psi at idle

Things I have tried:
-Mechanical Gauge - reads 38psi at idle - I think this is the proper oil pressure for this engine
-Replace oil pressure sensor & screen underneath it
-Scratch my head

What are my next steps here?

 

38 PSI at idle is fine. Whats it run at 1500-2000 RPM?

 

Hard to see my guage from in the cab because the hose is a little short but it definitly went up a few psi when I invreased rpm, maybe 45-55psi

 

You could possibly have a dirty filter screen under the oil pressue sender behinde the intake manifold.

 

As stated in my initial post, this has been replaced

 

Assuming you have a 1500 pick-up with a 5.3L. Minimum oil psi spec for VIN 0 is 22@1K,30@2K,and 33@3k. or for vin 3 is 24@1k,35@2K, and 38@3K. All taken at the top end. The oil pressure gauges are really pretty accurate. What you also need is oil pressure reading from the bottom end taken with an adapter that replaces the oil filter. Oil pressure readings should be taken with the engine at operating temp. I have run across numerous repairs for this issue. What I do is get the engine hot and monitor oil pressure top and bottom. When the gauge gets low is when I install the test adapter in place of the oil filter because I have had many restricted oil filters. Something you can try is when the engine is hot and showing 20psi oil pressure at idle, just put on a new oil filter and restart it and see if oil pressure comes up. Usually will come up about 10 psi if the filter is restricted. Hope you find this useful.

 

Thank you for this info.
It is the 5.3L vin 3 (LC9 engine)

I was taking my reading with my mechanical gauge at the bottom of the block, directly after the oil pump. I will check it again at the top where the sensor is to see if it is low at that point.

I do not have the oil filter adapter for my gauge, but maybe I will just change the oil and filter and see if that corrects it.

 

Perfectly fine oil pressures!