Oil pressure warning

2003 GMC ENVOY
199,376 MILES • 6 CYL • 4WD • AUTOMATIC
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SCOTT ALLEN BARKER
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My vehicle's oil pressure warning has started to come on the last 2 months when I'm only one quart low on oil. It will shut off the engine immediately until the quart is added.

When I add the quart, it's fine. Should I replace the oil pressure sensor?
Nov 30, 2020 at 5:57 PM
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KASEKENNY
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I would not think the oil sensor is the issue first. It could be but not the first issue. The first thing I would think is the oil is still a little low. Can you get a picture of the dip stick after you remove it, wipe it, then re-stick the oil and send a picture of where it is right now?

I am not suggesting you don't know how to read a dipstick but sometimes it appears to be a quart low when really it is about 2 or even 3 on larger vehicles like this with larger oil pans.

Next when is the last oil change that you had?

If the oil level checks out then we need to run through this guide for the other possible causes of low oil pressure:

https://www.2carpros.com/articles/high-or-low-engine-oil-pressure

The next thing is to check the oil pressure with a mechanical gauge just to see what it is. Let us know about this and we can go from there. Thanks
Dec 1, 2020 at 3:41 PM
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SCOTT ALLEN BARKER
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My regular mechanic verified 2 days ago that the oil was in fact only 1 quart low when the sensor shut off the engine. He also did the oil change about a month ago. He stated he's never heard of this problem before and wasn't sure if replacing the oil pressure sensor would fix the issue. So I thought I would get a second opinion.
Dec 1, 2020 at 4:45 PM
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KASEKENNY
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Yeah. I tend to agree so that means the way we need to confirm this has two parts. First to check the oil pressure as stated before, with a mechanical gauge to see what it actually is. The next step is to hook up a scan tool that can monitor the oil pressure through the ECM. They should clearly be the same. If they are not then I suspect the pressure sensor is reading low which means when you get a quart low, it thinks the pressure is lower then it actually is and it cuts the engine off. This would confirm the sensor issue. However, if they are the same then I suspect the ECM is the issue.

Let's start with the basics since you crossed off low oil and maintenance and get the pressure with the gauge then compare it to the ECM and go from there. I am sure your mechanic has a scan tool that can monitor this if you don't. Thanks
Dec 1, 2020 at 5:32 PM
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SCOTT ALLEN BARKER
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I will give your recommendations to my mechanic. Thank you. You've been helpful and kind!
Dec 1, 2020 at 7:00 PM
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KASEKENNY
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Sounds great. Let us know what happens. Thanks
Dec 2, 2020 at 7:02 PM