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P0521. Replaced the sensor. Sensor filter is missing. Code keeps returning.

wrd1972

Full Member
Joined
Jul 19, 2013
Messages
94
OK I have a 2007 LTZ with LC9 5.3L engine - 198K miles. Engine seems to run very nicely and smooth with no abnormal sounds.

So I got the dreaded P0521 oil pressure sensor code. But the sensor appears to be working meaning that it does not go to 0 or 80, when the engine is running. I have replaced the sensor and no change. The code returns.

I recently did the 4-cyl DOD delete and when I installed the new aluminum cover for the top of the block. I know I did not install the small sensor filter, that goes under the sensor. Did not even know there was a sensor there until now. So I can confidently say that small filter is not clogged. And I am pretty sure there was not one pre-installed in the aluminum cover. And just for giggles, I stuck an angled pick down the hole, and the pick goes pretty darn deep. So no filter found.

Oil pressure does seem a bit lower that it has been in years past. But still seems to be showing 10PSI per 100RPM. Maybe a bit less at higher RPM. So does this sound like simple low oil pressure causing the P0521? I cant see how the missing filter would cause it. But I am going to install a new one right away.

I am currently running standard 5W30 oil in the engine. Do I need to start using a different oil? Maybe a thicker oil?

Thanks for the response. And praying this is not a sign of a dying motor.
 
If the pressure gauge was stuck or sitting at 0 then I would say the sensor failed. It sounds more like it doesn't like the pressure level which is causing the code. Have you tried changing the oil and filter since this started? What brand oil and filter is in the truck right now? What's your pressure gauge showing at idle? I'll have to double check mine but I think it's usually at 40 at idle (warm) and hits 60 under acceleration.
 
Okay I have confirmed that there is indeed, no filter under the oil pressure sensor. I have reset the code again, and it keeps returning.

Here are some pressure that I am seeing:
Cold Idle = 50PSI
Hot Idle = 10PSI
2K = 20PSI
3K = 23PSI
4K = 30PSI
5K = 38PSI

Again the gauge is not showing in weirdness at all. No wild fluctuations or the sort. One person said the oil pan is leaking. But based on my experience, that does not cause low oil pressure.
So whee do I go now? Is this indeed a true low oil pressure situation due to 200K mile wear. :E: :E: :E:

 
I couldn't find a filter under my oil pressure sensor when I replaced it a couple of years back so you should be okay there.

Based on what you've posted, I would say you have low oil pressure or a faulty new sensor. I know that later model years run slightly lower (roughly 20 at idle) but if you're seeing 10 psi at warm idle that doesn't seem right at all. 60 psi at cold is what I'll see on my 07 as well, so once your truck is warmed up its as if the oil pressure nose dives.

I have heard of some oil filter brands causing this problem. Know what's currently on your truck?

 
What weight oil?

Oil pressure is frompump trying to move oil through main bearings & rod bearings as these have tight clearances.
If you use thin oil pressure lower then heavy oil.
IF oil temp is high pressure is lower then low temps.

Not all gages accurate. best bet is to install an eternal analog gage to compare.
 
In my opinion, this oil pressure issue sounds more like the o-ring on the oil pickup tube is bad. That's the issue I'm dealing with on mine. IF the o-ring is bad, imagine the oil pump trying to suck oil up a 'straw' that has a hole in it. Low rpm it sucks more air than oil, the higher the rpm the more oil pressure you see. To diagnose, make sure your engine is FULL of oil via the dipstick - don't want it even a half quart low. Then find a place to park where temporarily you can back up onto a curb, or something to lift the rear of the truck. This makes the oil in the pan move to the front of the pan, which will cover the o-ring sealed joint. Start the engine, and if you see good oil pressure - better than now - it is a bad o-ring. Best to diagnose when cold.

Hope it helps!

-AvyFanatic
 
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