2003 Venture Shows low Engine Oil Light, but the dipstick shows WAY over full

I turned on the car (2003 Chevy Venture) today and the “Low Engine Oil” display came on. I checked the oil (car had been parked on a flat surface overnight and engine was cold) and the oil was about 1/3 of the way up the dipstick, which is way, WAY past the full line. I let the car sit and warm up a little, checked again and the same level appeared. I am wondering what that means. After being on for a minute or so the engine oil light went off.

The check engine light has been on for about two days and when I went to check it yesterday the error code was p0171. Are the two related? Is there an easy fix for this or is this a sign of a serious problem? My know how is right this side of nothing.

Your engine has an oil level sensor mounted to the side of the oil pan.


More than likely this sensor has failed and requires replacement.


Tester may be right, but if the oil level is WAY over full, you need to get that down to the proper level. It is possible that the oil is foaming and the light you’re seeing is a low pressure light. I’d recommend a complete oil change.

I would just add the the oil situation and P0171 are unrelated. That code indicates a lean condition detected on bank one of the engine. I think on the venture that is the row of cylinders on the left side of the engine / rear of engine compartment.

The code will come from something like a vacuum leak (allowing too much air) or fuel delivery problem (too little fuel) or a problem with the O2 sensor on that side.

3400 motor. They have issue of failed intake gaskets and coolant in oil. Not a good combo. Is the coolant level ok? Could be warped intake also. How do u explain high oil level? Most cars burn oil and most folks deal with low oil issues. Not the opposite.

If Cavell is right, and he very well may be, do not start the engine even for diagnostic purposes until you purge the oil system and get fresh oil in there. Coolant in the oil can quickly destroy your engine.

I have to agree with the other responses here. In addition to coolant raising the oil level…fuel can also do the same thing. Make sure to have the oil inspected for both coolant and fuel. If it’s fuel then the fuel injection system will have to be diagnosed for the source of the problem.

Concur with those posting above, if there’s no explanation for the high oil level on the dipstick, best to not start the engine; instead drain a pint or so sample of the oil out from the oil pan drain plug, and take it to a mechanic for a visual inspection. If there’s water in the oil, since oil floats on water, the water will tend to go to the bottom of the pan, so if there is water/coolant present in the oil, it should be evident in the sample.

No water in the oil? If the last oil change, somebody simply made a mistake and put too much oil in – like they forgot to drain the old oil first say – that needs to be corrected asap too. Running an engine with too much oil in it causes all sorts of problems, including the possibility of causing leaking seals which will be costly to fix. It could cause a false sensor reading too I expect.

It would be helpful to know when the oil was last changed. Was it just before the light came on? If so, it was probably just an overfill. If your last oil change was months ago, something else is probably going on.

Thank you for the comments. The last oil change was probably about a month ago. The antifreeze has a habit of running low, but recently when I have checked it, it looked okay. (Last week I added some wiper fluid and checked it while I had the hood up anyway.) Again today when I looked at it, it seemed to be fine. I have to admit I don’t generally check the oil between changes unless the car complains about something. I just can’t understand why or how the level is so high. I have been reading (today) that high oil level is bad too, but the car hasn’t had any warnings about oil before, so would that mean that the level was fine for the past month? Or does it not warn about such things and maybe the car has just been running with too much in the system.

I will drain some and see what a mechanic has to say about it. How much should I expect to pay for such a test?

What’s a good way to test for fuel in the oil?

Again I really appreciate the help and input!

Like the others said, I strongly suspect your intake gaskets have failed. Unfortunately, this an extremely common problem with older GM V6 engines

That is most likely the reason the oil level is way overfilled . . . with coolant

If you drain the oil into a large tub, I wouldn’t be surprised if the oil that drains out is contaminated with coolant

SarahH wrote:
I have to admit I don’t generally check the oil between changes unless the car complains about something.

I hope you have a few thousand dollars sitting around to buy a new engine if your engine develops an oil leak or starts burning oil and you don’t notice that.