Oil pressure dropping to zero when stopped

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On my way into work this morning whenever I came to a stop my oil pressure dropped to zero & it said to turn off the engine.

As soon as I hit the gas pedal, went back to normal range. I understand the gauge is fake & there is a good chance it is a faulty switch possibly?

The big kicker here is we are supposed to drive from Texas to Mississippi tonight & I assuming this isn't something I want to mess with regardless of if it is just a faulty switch? My pregnant wife & toddler will be with me so no way I will drive it. Can possibly take my wifes car but didn't want to drive hers that far until we put new tires on it (planning on next week) so I may just end up having to rent a car.

2005 GMC Envoy 4.2L I-6 w/ about 120K miles.

Thoughts on situation? Anything I can do to make me feel comfortable driving it this afternoon. Not the most handy DIY person but am capable of basic stuff.

Thanks!
 
Classic symptoms of a failing oil pressure switch. Pull the green electrical connector for the switch and see if there is oil in it (another tell-tale sign of a failing switch). It's not too bad too change in a driveway with just a wrench.

That being said, it's not possible to 100% rule out a genuine low oil pressure problem without replacing the switch and/or putting a mechanical pressure gauge on the engine.
 
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Well I know the gauge is controlled by a switch. As you do. It's just on or off. What I don't know is where it is located to replace it, nor do I know if it being bad is what produces the "turn off engine" warning.

If it is easy enough to get to, you can buy a replacement part and a socket at autozone. I had one go bad on my tahoe. I don't recall getting anything more than a CEL light.

That said, mine was on the back top of the engine in a blind location. Took a little over an hour to figure out how to approach and complete the swap. I could probably do it again in 30 min.

AtlWrk seems to have it covered. Is it in a location that is easy to find? Would be the next question.
 
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Bottom, front, passenger side of the engine. Right above the oil filter. You should be able to get to it from the top IIRC.

The fact that you got the Stop Engine message means that it's not just a failing stepper motor in the cluster.
 
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Ughh... Of course this happens today. At least it happened before the road trip I guess.

I will check oil level. Anyone have a link for new switch? Can I find it on amazon? I could order & replace next week. Should I not drive it home from work?? I can basically get all the way home without stopping & other than the dash blinking when I came to a stop the car seemed to act/be 100% normal.
 
If your oil level is good, I would not worry about a faulty switch at idle.

Of course, if it stayed on ALL the time, there may be a concern with the pump.
 
Robbabob said:
If your oil level is good, I would not worry about a faulty switch at idle.

Of course, if it stayed on ALL the time, there may be a concern with the pump.
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If oil level and everything looks good, would you consider driving it 500 miles tonight & 500 miles back on Sunday? I could even completely change the oil & filter this afternoon before trip if that would be better.

Oil life is at about 50%. I run mobil 1 full synthetic.

Of course I need to check oil level after my meeting finishes here in an hour.
 
Update:

Just went out to the parking lot & turned the engine on & everything appeared to be 100% normal. No warning lights of any kind on the dash & the car started right up & sounded 100% normal as usual.

I let it warm up for a bit & then drove it slowly around the parking lot & braking to a stop periodically trying to see if the same issue would happen again. It never did once. Again, even this morning while the gauge was dropping to zero & saying low oil pressure turn off engine the car was acting/sounding 100% normal/good.

I also just checked the oil level & it was perfectly in the middle.

My gut tells me that I won't have any issues driving 500 miles tonight but then again I do not want to be risky or take the chance of ruining my engine if that is a possibility?

It won't be ideal to take wifes car or rent a car but if anyone strongly advises against not driving my car please speak your mind. You guys know a hell of a lot more about these vehicles than I do!

Thanks in advance!
 
If it was me, and the oil level was good, and the motor was not making any nefarious noises, I would probably drive it home with a quick stop at the auto parts store for the part and a tool.

Then I would replace said part after I got home and see if things were better. If so, I would probably drive it on the trip no worrys.

If I couldn't confirm because I couldn't replace the part, and my trip home was 5 miles, then I probably wouldn't take it on the trip.

That said, my trip home is about 40 miles. When mine went on the way to work, I had 20 miles to go, and about 2 miles and 10 min of stop and go traffic before I could stop. I rolled down the windows, listened for bad noises, and plugged in my obd scantool, which pointed to the oil pressure unit. Since it took me so long to get to a stopping point, I figured if it was something really bad it probably would have happened by then.

So I drove the rest of the way to work. Was I chancing it? Sure. But the gauge had been acting up for a couple days prior so I kinda had a handle on it. In the end it was fine.

But for you, if you have short trips it is possible it is something else on its way out. With such a long trip upcoming, I'd feel better if I left 3 hours later and fixed it, than to just chance it and see. And I rather spend the time and cost to fix it than rent a car.

Your mileage may vary....good luck!

Edit to add after your update. Take the time and try to fix it. If you find oil in the connector, or even if you don't, your going to feel better about driving it tonight.

I can't really think of a condition that would cause a pump failure, and then after sitting, the pump starts working again. I've seen mechanical pumps fail to self prime, but that would mean problems after it has been sitting..
 
It's only $45 and it takes about 15 minutes to change it out. If you had actually lost oil pressure your engine would be dead. So it is the switch, it would have sounded like hell for about 1 minute and locked up otherwise.
 
BlazingTrails said:
It's only $45 and it takes about 15 minutes to change it out. If you had actually lost oil pressure your engine would be dead. So it is the switch, it would have sounded like hell for about 1 minute and locked up otherwise.
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Thanks!

I am going to stop & pick up the part now & see about replacing it. Front passenger side above the oil filter?

After I drive home if it seems normal & I get the part changed out I won't have a problem driving it, but already mother - in - law is insisting we take her new Explorer to be on the safe side so it could end up working out perfect!

Thanks again for everyones help.
 
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Well I like the thought of the new car....but I think I'd just take my own. Hate having to deal with the issues of accidents, or just door dings, with other peoples stuff. If your worried about getting stranded, call and add on roadside assistance to your insurance policy if you don't have it...its pretty cheap and extra peace of mind.

I think its the switch as well. Replace it and go about your business, have a good trip!
 
He needs it today so Amazon is out.

In 4 years of being with this platform, I have yet to hear of a oil pump failure. These are very reliable gerotor pumps driven directly from the front of the crank.
 
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Be careful with channel locks. If you squeeze too hard you can distort the metal and cause the sensor to leak. I've done it on an '85 Buick.
 
Thanks everyone for the replies. I picked up the part but wasn't able to change it out on Thursday & ended up driving MIL's explorer. Worked out well.

Car has been driving fine though & it hasn't happened again.

BIL & I did jack it up quick & get under and take a look... Looks like it'll be easiest to access/change it out from below but above was mentioned best to access from the top?

I may order that one off Amazon & return the other to Autozone, thanks for the link.
 
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