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Discussion Starter #1
I got code P0521 Engine Oil Pressure Sensor/Switch Range/Performance DTC so I replaced the oil pressure sensor. After replacing the sensor I cleared the code.

After driving 30 miles the code came back.

Is it possible the sensor I got was faulty? It was the a non-genuine APDTY sensor from Amazon part 12616646.

Should I get a genuine AC Delco 12616646 and try again?
 

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Based on the outcome of these two threads, would say it might be worth a shot to replace the APDTY oil pressure sensor with a real Ac Delco, and if it works, then return the APDTY as defective. Have only used APDTY products a handful of times and it is generally something like a mirror or headlamp assembly i.e. something non-electrical.

http://www.g8board.com/forums/42-canada/274706-man-vs-p0521.html
http://www.g8board.com/forums/5-v8-engine-tech-l76-ls3/274001-argg-p0521-p0523-codes-oil-presure-related-wifes-car.html
 

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Also, did you replace, or clean, the small screen/filter located directly below the sensor?

JAM
Good point. Beat me to it. The part number is 12585328.
 

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Glad to hear this. My sensor and filter should be here tomorrow. Also got the correct socket, so hopefully it's an easy job.

Side note: I reset my CEL not long after it came on, and haven't had the code pop back up since. I've driven around 100 miles.
 

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Sounds great. Be sure to send back the defective APDTY oil pressure sensor for a refund presuming it's still within their thirty day return window.
 

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Discussion Starter #8
So the genuine sensor worked for 6 weeks without issues and now the error has come back.

Could it be another faulty sensor?

Are these cars so sensitive to which sensor you use?
 

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Changed my sensor about a month ago. I got the CEL the next day after changing the sensor, but then did an oil change that day and the CEL has been off since.

I'm guessing my original sensor wasn't bad, and that by doing an oil change, I just put a band-aid on something like failing lifter or cam bearings. Granted I'm happy to have the band-aid for another couple months.

When I changed the oil, it had only been about 4500 miles on Mobil 1 5w-30. I used the same oil and a Delco PF48E filter.
 

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Discussion Starter #10
I did notice the oil was on the high end of the fill during last oil fill. Could it be there's a bit too much oil in there?
 

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The oil level should always remain toward the upper portion i.e. safe zone on the dipstick. Never exceed the upper mark nor go below the lower mark. Too much oil makes it harder on the seals. Too little oil makes it harder for the internal components to stay properly lubricated. Would suggest checking the oil pressure with a manual gauge and see if the reading is within range. If so, it lets you know either the sending unit is faulty or something is not right within the circuitry. If not, then there is another underlying issue causing the reading to register below normal. Regarding different sending units, have read where others have reported cars being finicky when a non-AcDelco unit is installed. Concerning the quality of AcDelco parts, on several occasions fellow members have had both alternators and radiators fail within less than two months after being installed. Unfortunately, not much of anything is as good as it used to be and the bean-counters aren't making things any better.
 

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I've been having this P0521 code as well for 2 or 3 weeks now. Initially I changed the sensor, then the oil and filter. It was only like 3500 miles since I had a new set of lifters (non-DOD) a bigger camshaft, new oil pump, valvesprings installed. The oil was surprisingly dirty... first time EVER, and on a very short change interval. When buying the oil, I saw Mobile1 Extended Service in the 5 quart jugs for a good sale price, so I got it and a new WIX XP filter. The code came back almost immediately. I run Torque on my smartphone, and after adding the engine oil pressure plug-in, I am able to monitor what that sensor is putting out to the ECU. Upon cold starting, I get 40 to 45 lbs. pressure at idle. After warming up, it drops to 22 to 26 at idle. But on really warm days, after 30 or 40 miles of driving, when it comes to idle the pressure drops to 18 to 21, occasionally even lower. I've been monitoring the pressure, and the ECU is throwing the "Pending Code" when the pressure is in the mid to upper 20s... no clue why it's doing that. The freeze frame data doesn't include the oil pressure readings, but I've been looking right at it when it trips the CEL.

I read on here about the little filter below the sensor, so I bought one, pulled the sensor, and went "fishing" for the filter. I got nothing, so I looked down there with a mirror and lights. NO FILTER! Then I realized when my engine builder did the rebuild, we used a new valley cover without all the AFM solenoids, etc. So obviously there's not gonna be a filter there either... DUH!

I went and bought some Lucas Synthetic Oil Stabilizer (@$16\qt!) and added half a quart. The pressures are up across the board, but not enough to stop the codes altogether. I gotta find a way to let like a quart or quart and a half of oil outta the crankcase to add a bit more Lucas in there. I believe that Extended Performance stuff is just too thin at full temp. The Lucas stuff is SUPER THICK and brings up the overall viscosity a few clicks. Short of dumping the full 8.8 quarts in the garbage and getting another 8.8 quarts of some other good synthetic oil to replace it with (about a $150 expense) I'm gonna try to "fix" the (new) oil that's in there.
Has anyone else ever had any pressure issues with M1 Extended Performance oil? I've always used 5W30 oil... I'm thinking on mebbe trying a 5W40 next time if I can find any anywhere. I'm out of ideas what else to try...
 

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Have you mentioned the P0521 issue to the engine rebuilder? Is so, what was their response? What type of warranty did they provide on the work performed? Does the oil pressure fluctuate with the rpm's of the engine? On a totally unrelated vehicle, the oil pressure drops to almost zero once the vehicle reaches full operating temperature. Determined it is most probably a worn camshaft bearing. Decided to forgo repairing it since if the engine took a crap, could finally justify replacing it with a small block V8. :grin2:
 

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Yes, I talked with my engine builder about this... He said he didn't remember if he changed the O-ring on the oil pick-up tube on my motor, only that he does when they look raspy. He also said if it was the O-ring, I'd be seeing only 5psi all the time, not full pressure on cold start, dropping with temperature. I gave him all the hard parts he used, including a new GM high volume oil pump (i bought all the parts from Texas Speed). He completed the build just before X-Mas, and I didn't see any issues untill mid May... doesn't sound like defective pump. I gotta believe it's that damn M1 EP oil. I've been trying to find confirmation of my hypothesis on Bob Is The Oil Guy.com. The viscosity index is kinda screwy for that Extended Performance stuff, and the ad-pack has a ton of friction inhibitors innit, but I've not found anything yet that confirms the actual viscosity vs. it's heat handling properties... YET! Still looking.....
 

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Discussion Starter #16
Three oil pressure sensors and months later the issue was resolved by a simple oil change.

Maybe the oil was slightly overfilled or maybe a defective oil filter.
 

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Three oil pressure sensors and months later the issue was resolved by a simple oil change.

Maybe the oil was slightly overfilled or maybe a defective oil filter.
Luckily, I only changed the sensor once, but yeah, an oil change has kept the light off for months now.

I'm doing my dod-delete, cam, and a bunch of other work the first week of August. We'll see how the cam bearings look. Fingers crossed they're still decent.
 

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Great you were able to resolve the issue and appreciate the thread update. For the most recent oil change, did you use the same oil brand/weight and filter as previously?
 

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Discussion Starter #19
Great you were able to resolve the issue and appreciate the thread update. For the most recent oil change, did you use the same oil brand/weight and filter as previously?
I like to update to help others in the future.

Before I used Pennzoil Synthetic and PureOne filter. This time I used 50% Mobil 1 High Mileage Synthetic and 50% Castrol Magnetec and Mobil 1 extended Mileage filter.

I really think the oil was either slightly overfilled or an issue with the filter. Highly doubt it had anything to do with the quality of the oil itself since Pennzoil stuff is pretty good.
 

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I really think the oil was either slightly overfilled or an issue with the filter. Highly doubt it had anything to do with the quality of the oil itself since Pennzoil stuff is pretty good.
I guess I hadn't really considered the filter as much. Maybe that's more the cause. I agree, there's no way Mobil 1 (in my case) should've been shot at 4500 miles.
 
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