2015 Duramax: Cold Oil Pressure Bounces Off "0"

jasonvp · January 31, 2019

Hey folks -

Within the last month or so, my 2015 Duramax has been behaving a bit strangely when cold. The definition of "cold" in this case is merely anywhere between 10-25*F, give or take. After a cold start, the oil pressure bounces right up to where it should be during idle. However, shortly after I put it in gear, drive down the road, and round a corner, the pressure bounces off "0". It usually happens twice in quick succession and I get the requisite "TURN YOUR ENGINE OFF, YOU MORON!!" alarm. After each bounce off 0, the pressure shoots right back up to where it needs to be, and all is good.

This only happens when the truck is cold. After that point, I have no more issues with it until it sits in the cold for a few hours.

My last oil change receipt says they used 10qts (which is correct) and they used the appropriate 15W40 oil, which for these temps in Northern VA should be perfectly fine.

Bad sensor that doesn't like to be cold, maybe? Should I just have them change the oil and do it again? The oil level seems correct based on my last "HOT" check this weekend, so I'm not losing any. Any other thoughts?

avalonandl · February 10, 2019

I would say you have a oil pickup issue.

jasonvp · February 10, 2019

1 minute ago, avalonandl said:

I would say you have a oil pickup issue.

Pardon my ignorance, but wouldn't that result in some potentially disastrous engine problems?

avalonandl · February 10, 2019

Yes I would say so.

Look at the facts- it happens only when VERY cold and not fully warmed up:

This means pressure is dropping: one choice is oil is too thick and not flowing, one is bad sensor, another is low oil-you checked that. Oil pick up is another, your pumping cold oil into the top of the engine and it hasn't drained back and pickup is sucking air.

Warm the truck up is another choice.

redwngr · February 10, 2019

A guess, but maybe be a sensor or harness connection that once it's warm enough tightens the joint so it reads correctly??

Regardless it needs to get fixed.

Especially if it's not the sensor or sensor circuit.

I've had years of dmax 'starts' at those temps and lower, using 15W-40, and have never had one do that.

Boots · June 4, 2019

I have the same problem, did you find out what the issue was??

jasonvp · June 4, 2019

1 hour ago, Boots said:

I have the same problem, did you find out what the issue was??

Not yet; I haven't had the opportunity to have my dealer look into it thoroughly. An "off-the-cuff" guess from him was one of the sensors was bad but he wasn't sure.

Paintor · June 8, 2019

On 2/10/2019 at 10:37 AM, avalonandl said:

I would say you have a oil pickup issue.

He says it only happens when he goes around a corner. Agree. Or one very very loose oil pressure sensor wire, but that should also read 0 oil pressure on bumps.

jasonvp · September 18, 2019

Sorry for the long delay in reporting back in; I just had the truck serviced. I've been busier than a 1-legged man in an ass-kicking contest.

Diagnosis: pressure sensor was FUBAR'd. And there was a teensy bit of oil leaking around it, too. Which is interesting because there's nothing on my garage floor. They replaced it and I noticed an immediate change in the oil pressure reading. Prior to the change it was always on the higher side, but not at maximum. Now it just generally floats around between 1/4 and mid pressure.

The annoying thing: they claim this swap was NOT covered under the 5/100 power train warranty. Even though it's a sensor attached to the power train, apparently it's part of the (expired) 3/36. Hm. That seems suspect, but I didn't press the issue because I wanted it fixed.