Gurus help needed. Code P0521 Yukon Denali

Im kind of lost here and looking for some help from the Gurus. Ive had the code P0521 in my 2008 Yukon denali. It refers to bad circuit and/or bad oil sending unit. I changed the part and I still have the code from time to time.

Ive been researching the forums and the internet and I know the 5.3l engines have that faulty code is due to the little screen under the oil sending unit, it gets too much crap in it and shows the code and low oil pressure reading on the dash. I know the 6.2l engines without AFM don't have that screen, any ideas? My gauge is also showing low oil pressure after the car has been warmed up. It starts above 40 and slowly goes down to about 10 after maybe 10 minutes of driving.

Any help or information is truly appreciated, thanks in advance!

anyone? ive been searching the web and haven't seen a problem like this in a 2007-2008 denali without afm with a solution. I checked a couple youtube videos showing the same problem but no solutions. Cant believe nobody in this forum has experienced this in their denalis

change the valve lifter oil filter. Check the video below for instructions


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There is no filter in the 6.2 with no AFM

I never had the code but traded in an 08 Sierra Denali in on a 09 yukon denali. I noticed the oil pressure was much lower and down at the 15 mark from time to time. Drained the crappy dealer oil and filled her up with pennzoil platinum and a wix filter and low pressure is gone. Had 79k on the clock when I got it.

The connectors are prone to shorting. We always change them with the sending unit at the dealer.

Tw1st3dm3ch said:

The connectors are prone to shorting. We always change them with the sending unit at the dealer.

Click to expand...

Thanks for your response. How can I check that to see if that's my problem?