Oil pressure sending unit range ???

[kbuskill]

So I recently (2-3months ago) replaced my oil pump with the high volume/high pressure pump from Mellings and it completely eliminated the lifter ticking that I was experiencing from time to time.

Before the new pump I would have 40psi at idle with a cold engine and around 20-25psi at idle with a hot engine.

Now with the new pump I have a little over 60psi cold idle and a little under 60psi hot idle and about 65psi while cruising.

The "problem" I have now is I keep getting a CEL and the code is

P0521 (Engine Oil Pressure Sensor/Switch Circuit Range/Performance)

Now some background. When I first did the oil pump, along with a bunch of other work, I pulled the oil pressure sensor and removed the screen filter underneath it and reinstalled the sensor.
I never had any problems or CEL for oil pressure before and didn't have the P0521 pop up for a couple weeks after installing the new pump.
When it did pop up I checked it and cleared the code and took a 1000 mile trip each way plus the local driving around for the week we were out of town then got home and drove around locally for another couple weeks before the code reappeared.
I checked/cleared it again and it reappeared again within a day and I did the same thing again and it reappeared again within a day.

So my question is...

Does anyone know what PSI range the ECU is looking for as "normal pressure"???

I just hate to go to all the trouble of removing the intake to change the sensor only to find out there is nothing wrong with the sensor that is on the truck and the ECU is just setting the code because the oil pressure is "too high".

Also if it is "too high" I am thinking of reinstalling a new screen filter to try and keep the sensor from "seeing" so much pressure, although I doubt it will help much, I have read others posting that removing the screen showed an improvement in oil pressure on their gauge although I am not certain how clogged their screen may have been.

My oil pressure gauge works flawlessly which is another reason I am doubting that there is anything actually wrong with the current sensor.

Any and all help would be appreciated. If no one can give me a definitive answer on the range the ECU is looking for then the only thing I can think to do is call Black Bear and see if they know or can look into the ECU's programming for the answer and if it is out of range then my only option may be to get a tune and have them change the parameters on the oil pressure range to a higher setting.

 

[kbuskill]

Bump.... anyone????

 

[HiHoeSilver]

Wish I could help. This is a really good question. Sub'd. Side note: I know you already knew this, but changing that sensor takes 10 mins. No intake removal necessary.

 

[kbuskill]

Wish I could help. This is a really good question. Sub'd. Side note: I know you already knew this, but changing that sensor takes 10 mins. No intake removal necessary.

I don't know about that... I pulled my intake when I did the other work just to replace the intake gaskets while I was doing everything else and I pulled the screen filter below the sending unit while it was off.

I have seen videos of people changing them with the intake in place and it doesn't look like much fun... lol

 

[HiHoeSilver]

I don't know about that... I pulled my intake when I did the other work just to replace the intake gaskets while I was doing everything else and I pulled the screen filter below the sending unit while it was off.

I have seen videos of people changing them with the intake in place and it doesn't look like much fun... lol

I've done it. Piece of cake.

 

[kbuskill]

May try it IF it comes to that... I still hate the idea of changing it only to find I may still have the same issue.

 

[HiHoeSilver]

May try it IF it comes to that... I still hate the idea of changing it only to find I may still have the same issue.

With ya there.

 

[Rocket Man]

That's a $30 part and I bet you wish you'd just replaced it when you had the manifold off but hindsight as they say. It is fairly easy to do without removing the manifold though, about as hard as spark plug #8 (the one on the passenger side rear). You pretty much have to do it by feel but it's not too hard. I wouldn't doubt it's the sensor since the range your gauge is showing is fairly normal; it could be that the sensor is having hiccups from time to time that your eyes might not see on the gauge because it either happens fast or you're not looking at the gauge when it happens. The ECU watches every second.

 

[#1taho]

There is a oil sensor near the starter. I am not sure what it does. But maybe that's part or your problem. I am subbed also to find out what your out come is.

 

[kbuskill]

That's a $30 part and I bet you wish you'd just replaced it when you had the manifold off but hindsight as they say. It is fairly easy to do without removing the manifold though, about as hard as spark plug #8 (the one on the passenger side rear). You pretty much have to do it by feel but it's not too hard. I wouldn't doubt it's the sensor since the range your gauge is showing is fairly normal; it could be that the sensor is having hiccups from time to time that your eyes might not see on the gauge because it either happens fast or you're not looking at the gauge when it happens. The ECU watches every second.

Like you said, hind sight is 20/20....

BUT in my defense I never had any trouble with it prior to changing the oil pump... gauge has always worked perfectly and never had any CEL or anything else that would make me think that it needed to be changed out so I simply removed it to take out the filter screen below it and reinstalled it.

Also what makes me think it is not the sensor is it doesn't have a CEL for voltage high or low... it just says range performance.

I PM'd @JennaBear and asked if they could help me out with this question about the range that the ECU is looking for, so we will see if they can help out.

On a positive note, I have great oil pressure and ABSOLUTELY NO TICKING from my lifters like I would get from time to time before changing the oil pump.

 

[kbuskill]

There is a oil sensor near the starter. I am not sure what it does. But maybe that's part or your problem. I am subbed also to find out what your out come is.

My Brother has a 2012 Silverado and he was trying to tell me the same thing but I don't believe my 2008 has a second sensor... at least I don't remember seeing one while changing the oil OR while I had the oil pan off... BUT I have been known to be wrong on occasion.

If you are referring to the one on the side of the oil pan near the starter then I know for sure mine does NOT have that one because I remember thinking that it was odd that it wasn't there after reading about it.

 

[kbuskill]

Here is the reaponse I received from Justin at BBP...

Hi Ken,

That is unfortunately not something that I can see or alter. I only have access to the low oil pressure parameters. It would be easy to disable that DTC though for you. As long as the gauge is working, you can likely rule out an issue with the sensor.

Justin


I just thought I would update this thread with the info in case anyone was wondering.

So at this point I am still undecided on what I am going to do. I may just go ahead and throw the sensor on it since I have already bought it and see what happens. With a little luck it will fix my issue.... but I am certainly NOT holding my breath.

Maybe I will have time this weekend...I will keep you all posted.

 

[kbuskill]

So to update this thread...

My oil pressure gauge stopped working about a week ago, cranked up the truck and 0 oil pressure on the gauge. If I had not just changed the oil pump and O-ring on the pickup tube, I would have been freaking out but when I saw no oil pressure I immediately rolled down the window and listened for any ticking or tapping and there was none so I drove it for the week and waited until I had time to change it this weekend.

So I changed it today without removing the intake manifold, took about 30 mins with a socket, swivel, extension and ratchet. I cranked the truck up and still didn't have any oil pressure....
































for about 15-20 seconds, then it jumped up to its normal 70 psi cold idle pressure.... lol

I cleared the 4 codes, which were for

1. Oil pressure range
2. Oil pressure switch voltage high
3. Lean bank 1
4. Lean bank 2

Not sure why the lean bank 1, 2 codes were set, maybe it had something to do with the oil pressure gauge not functioning?

Anyway so far so good... no CEL or codes yet... I guess only time will tell if I get the oil pressure performance range code again.

I guess I will see if the lean codes show back up before I start changing O2 sensors.

 

[Rocket Man]

Awesome, looks like you have it fixed. Update in awhile so we'll know for sure it was the sensor.

 

[kbuskill]

Awesome, looks like you have it fixed. Update in awhile so we'll know for sure it was the sensor.

So the CEL is back on again.... same p0521 oil pressure range performance code that I had before the gauge stopped working.

I clearly have more pressure than what the ECU considers normal and need to figure out how to trick the ECU into not "seeing" that much pressure.

Couple ideas I have come up with.

1. Drill the hole in the bottom of the sensor out bigger.
2. Make the hole on the bottom of the sensor smaller.

Not sure which if either would work. Smaller hole on a garden hose makes more pressure BUT in pneumatics a larger cylinder (think air cylinder with an extendable rod) requires less PSI to create the same amount of lift.

3. Get Blackbear to flash the ECU to ignore that sensor, which I don't like because it is my wife's truck and I am afraid if it did lose oil pressure she might not notice without a CEL.

In this instance the ECU gets a higher voltage reading the lower the oil pressure...
So 5 volts = 0 PSI
and 0 volts = 80+ PSI

My truck with the new pressure sending unit reads about 72 PSI when cold and reads about the same while accelerating after it is warmed up. When warmed up it idles with about 55-60 PSI.

 

[mals]

So the CEL is back on again.... same p0521 oil pressure range performance code that I had before the gauge stopped working.

My truck with the new pressure sending unit reads about 72 PSI when cold and reads about the same while accelerating after it is warmed up. When warmed up it idles with about 55-60 PSI.

I have no idea what normal is, but I generally take the middle point of the gauge to be what the manufacturer is expecting (40psi in our case). In my Yukon (with a replacement oil sending unit) the cold start pressure is just about 40psi, warm idle is a little below 30psi, under normal load it comes back up to 40psi, and then gains about 2psi for every 1000 rpm under acceleration. I don't think I've ever seen my oil pressure over 50psi. That's with a stock 6.0L, 165k miles, and 5W-30 synthetic oil.

 

[Rocket Man]

You could probably use a resistor on the wire that comes from the sensor, not sure what value you'd need but if you have a meter you could try some different ones until you get an acceptable voltage.

 

[HiHoeSilver]

You could probably use a resistor on the wire that comes from the sensor, not sure what value you'd need but if you have a meter you could try some different ones until you get an acceptable voltage.

I thought of this, too. I have done it on O2 sensors to trick out a CEL. The problem here I think is that a resistor is just going to tell the ECU that the pressure is even higher than it already is...

 

[Rocket Man]

I thought of this, too. I have done it on O2 sensors to trick out a CEL. The problem here I think is that a resistor is just going to tell the ECU that the pressure is even higher than it already is...

Normally a sensor reads higher voltage as it goes up but you can check with a meter and have someone rev the engine while you read voltage. Voltage should go up as oil pressure increases.

 

[HiHoeSilver]

Normally a sensor reads higher voltage as it goes up but you can check with a meter and have someone rev the engine while you read voltage. Voltage should go up as oil pressure increases.

I'm pretty sure @kbuskill is right on this one. 5v reference. 5v return is 0 psi, 0v return is 80+psi. But you're right, might be worth checking with a meter.