GM Oil Pressure Warning

The wife just called me for a rescue. It seems that her truck gave her a low/no oil pressure warning. She shut it off, restarted it, and the warning came back on. She says the oil pressure gauge was pegged at 0, but I have no way of verifying that.

It’s a 2012 Tahoe with the 5.3 L motor. It had a fresh oil change about 400 miles ago (I usually do it myself and use Mobil 1 5W-30, but the dealer changed it when I had it in for service 2 weeks ago), there is no evidence of leaking, and the oil level is fine. I got there, looked for a pool of oil under it (none), checked the oil level (fine), and started it up. No warning for me, and the pressure gauge is registering oil pressure. The photo is from idle. It hovers around 40-45 psi when driving. I drove it a few miles home, and it ran fine and gave me no warnings.

What’s going on here? I don’t want to bring it in if I can’t replicate the issue, but I don’t want my wife to get stranded, either.

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Tupical bad gm gage/sending unit. Common issue.

not unusual for a 5.3 to do that but it can be a bit involved so heres what can happen.
the O-ring that seals the sump to the block has shrunk or cracked allowing the pump to suck air when the oil is cold,not good as it is not pumping oil when it does this.
one way to check it but dont drive it that way when doing what I tell you to try,
overfill the crankcase by three quarts.
if it works okay then,the O-ring is bad,what you are doing by overfilling it is getting the oil level above the O-ring sealing it up with oil.
dont forget to drain the excess oil before driving it again,too many reasons as to why,just dont do it.

the second thing is the 5.3 is prone to having the oil pressure switch go bad,not a big deal to change but not the easiest thing to get to.
it is in the back of the motor towards the drivers side and directly behind the intake manifold ,you will need an extension with a universal and the proper socket to get it.
there is a screen below that sensor that may be plugged with metal filings,if it is there is a bearing going out and that is where the debris is coming from.

if in fact it is losing oil pressure due to a bad O-ring,dont drive it very long that way as it can spin a cam bearing,usually the third one back.
if it is the O-ring,removing the pan is required to get to it,look up at the camshaft to see if the bearing has slipped out,if it has,time to pull the motor unfortunately.

hopefully luck is on your side and its simply a bad oil pressure switch.
good luck !

Iowaboy1 wrote:

hopefully luck is on your side and its simply a bad oil pressure switch.

Does the fact that it’s functioning normally now tell me anything? Is there a way to test the oil pressure sensor, or is it just a “replace and see if the issue happens again” type thing?

replace it and see what happens,if it continues you have other problems sad to say.
the sensor runs about sixty bucks and change and about an hours labor,but,be forewarned,it use to be that factory book time was around four or five hours as the “right way” to get at it was to pull the intake manifold.

trust me,I can do it in under an hour easily without removing the manifold.
hopefully by now someone has re-written the labor times on it,if not and the installer wont budge on the time,you are looking at several hundred dollars to change it out.

I would try the oil pressure sensor first, beings it would be the easiest thing to try. I am sure there is an ohm tolerance that can be looked up for the operating range of the oil pressure sensor. Did your wife say if the oil pressure just dropped to 0 or did it slowly get lower and lower? Iowaboy1 may be able to help with a few more details, judging by his post he seems quite knowledgeable on the subject. I do a bit of wrenching mainly for fun but am in no way an expert, but I have had gauges and sensors go and the needle of the guage either twitches or falls dead if it is a guage or sensor issue.

I had the same thing happen to a GM 6.2 in my Denali. It was unnerving for sure. The sensor was a PITA to get at and no way would I have been able to get it out with my hands. I had it done at a nearby repair shop and it wasn’t too bad. It would be easy to do if you can get your hands in there. Its just that it was almost underneath the firewall on mine.

Not fun. I’ve had to do the O-ring on my last truck. It’s really not hard to do, just time consuming for such a stupid simple part…

I could be wrong, but I believe if you bring it to a dealer, they will recommend you do both just to be safe. Oil pressure isn’t something to mess around with…

If its not the o ring then There is a screen underneath the oil pressure sensor..its plugged…it is a very fine screen and plugs easily…my 09 gmc sierra did it to me 3 times in 8 months…needless to say I traded it with 68k bc I was advised that all hell breaks loose on the body style around 70k…oil pressure lifters yada yada yada didn’t want to dump a couple grand into it

Good luck to you but I would start with the pressure sensor screen then the sensor itself and then the o ring

Brady Valberg wrote:

If its not the o ring then There is a screen underneath the oil pressure sensor..its plugged…it is a very fine screen and plugs easily…my 09 gmc sierra did it to me 3 times in 8 months…needless to say I traded it with 68k bc I was advised that all hell breaks loose on the body style around 70k…oil pressure lifters yada yada yada didn’t want to dump a couple grand into it

Good luck to you but I would start with the pressure sensor screen then the sensor itself and then the o ring

May I ask what kind of oil and how often do you change it?

Vehicles, puke.

Good luck man hope it’s a cheap fix for ya.

mxskeeter wrote:

May I ask what kind of oil and how often do you change it?

Is this question for me? I run Mobil 1 High Mileage and change every 6K. I bought it with 70K on it and am at 94K now. No idea what was run in it before that. Dealer changed it 500 miles ago, and I don’t know what they put in.

Ralph Wiggum wrote:

The wife just called me for a rescue. It seems that her truck gave her a low/no oil pressure warning. She shut it off, restarted it, and the warning came back on. She says the oil pressure gauge was pegged at 0, but I have no way of verifying that.

It’s a 2012 Tahoe with the 5.3 L motor. It had a fresh oil change about 400 miles ago (I usually do it myself and use Mobil 1 5W-30, but the dealer changed it when I had it in for service 2 weeks ago), there is no evidence of leaking, and the oil level is fine. I got there, looked for a pool of oil under it (none), checked the oil level (fine), and started it up. No warning for me, and the pressure gauge is registering oil pressure. The photo is from idle. It hovers around 40-45 psi when driving. I drove it a few miles home, and it ran fine and gave me no warnings.

What’s going on here? I don’t want to bring it in if I can’t replicate the issue, but I don’t want my wife to get stranded, either.

Perhaps your wife is feeling neglected? This might be her cry for attention. Have you been spending too much time away from home? I have seen this before…

mxskeeter wrote:

<div class=”d4p-bbt-quote-title”>Brady Valberg wrote:</div>
If its not the o ring then There is a screen underneath the oil pressure sensor..its plugged…it is a very fine screen and plugs easily…my 09 gmc sierra did it to me 3 times in 8 months…needless to say I traded it with 68k bc I was advised that all hell breaks loose on the body style around 70k…oil pressure lifters yada yada yada didn’t want to dump a couple grand into it

Good luck to you but I would start with the pressure sensor screen then the sensor itself and then the o ring

May I ask what kind of oil and how often do you change it?

I ran Schaeffer fully synthetic in that truck changed every 3-5k

An update: The Tahoe started up normally this morning. Oil pressure was fine on startup. I drove 6 miles to work, and the oil pressure behaved as it should.

I’ll probably make a call today to get it in and have the sensor replaced.

Walleyestudent Andy Cox wrote:

Perhaps your wife is feeling neglected?

So, maybe she just wanted a nooner?

Ralph Wiggum wrote:

<div class=”d4p-bbt-quote-title”>Walleyestudent Andy Cox wrote:</div>
Perhaps your wife is feeling neglected?

So, maybe she just wanted a nooner?

^^^

Hope you obliged…

Ralph Wiggum wrote:

<div class=”d4p-bbt-quote-title”>Walleyestudent Andy Cox wrote:</div>
Perhaps your wife is feeling neglected?

So, maybe she just wanted a nooner?

LOL
At least she called you!

Well, the Tahoe has behaved since that one incident. I had the sensor changed today, just to be on the safe side.