Callisto1

Yesterday I finally had some time to tackle the oil pan, but I also needed to change the fuel filter, which took too long because the drivers side air intake is a bear to reconnect properly, especially if the engine is hot. But I finally finished, put the car up on the lift, drained the oil, and started looking at how to drop the oil pan. Mea Culpa, I printed the instructions to have all the torque specs, but I hadn't yet reviewed step by step carefully. And when I did I realized you have to hoist the engine up to access the oil pan. Not gonna happen in the 3 hours before I had to pick up my kids at school. Put the drain plug back, filled with 229.52, and what do you know, no more check engine oil level warning. Draining the pan solved the problem, at least temporarily.
That makes me want to go back when I have more time and do the job properly, to see what kind of crud is sitting in the bottom of the pan and possibly blocking the sensor. FWIW, I change oil every 5000 not 10,000.

jonathankreb

I have been getting the false "check oil at the next fill-up" warning for some time on my 2008 GL320. I change my oil every 10,000 miles. The false oil level warning typically only comes on on long road trips, when the vehicle is running at highway speed for several hours at a time. I am not sure whether I saw this warning prior to my last oil change or not, but I think I did. So I too am planning on changing out the sensor, and I too am a litle discouraged at having to lift the engine in order to be able to remove the pan. I have a road trip coming up in less than a week, and am reluctant to engage in major surgery so close to my departure date. The main question I have is: will further degradation/failure of this sensor cause something more crippling to happen, ie., the engine automatically shutting off thinking it is in a low oil condition, or going into limp mode?

DennisG01

Jonathan, I don't know the answer, but... what happens if you disconnect the sensor? Try it while you're in you're in your neighborhood and see what happens? Worst case, plug it back in. It's not like you're going to do any damage to anything.

jonathankreb

Huh...Not a bad suggestion. I guess that from the sensor replacement instructions, I had assumed that the sensor's electrical connection was within the oil pan, so not accessible without disassembly. I'll look at my replacement sensor to see if there is any indication of where the connection takes place.

DennisG01

You could very well be right in regards to the location. I honestly don't know - I was just spitballin' an idea. I was imagining "assuming" that the switch was inserted through the side of the pan and the connector was on the outside.

As a follow up, if it is in the pan, where does the switch's harness come out and connect into "something else"? Can it be disconnected there? Do the wires, intact, go through the pan to get out of the pan? It would have to be an awful secure seal to keep water out. Or is there another connection there? I know... I'm probably gonna get warned by the home plate ump...

Callisto1

I understand why you wouldn't want to undertake major surgery before a long road trip. May I suggest you simply change the oil before your trip. That cleared up whatever was affecting the sensor on my vehicle.

alx

you have sludge on the bottom of the oil pan and adjacent surfaces. before next oil change warm up oil to operating temp and pour a can of seafoam in the oil. let it idle for 10 minutes and drain immediately.

if oil level sensor still false positives, replace.

good luck

jonathankreb

The oil change with Seafoam is worth trying. Would sure save a lot of effort if that is all that is wrong. I was just thinking back as to when this started, and it began a little over a year ago, and I have changed the oil since then, so I had convinced myself that an oil change would not be the hoped-for quick fix. I also determined that the electrical connection of the sensor penetrates the engine housing vertically and the connection is visible just below the harmonic balancer. I disconnected it and drove around the neighborhood, and all that happened was the "check oil at next fill-up" warning came on within about 10 minutes of driving, but nothing any more dramatic than that. I would have expected a check engine light as well, but nothing, So at least I have a little more peace of mind that even in a complete failure, I shouldn't be left stranded on the side of the road.

Thanks!

DennisG01

Good - I'm sure that's a relief that the oil level switch won't cause a limp mode. It makes sense. Low oil pressure, however, that would be a different story.

I used the SeaFoam trick on my '97 BMW's VANOS system that was sticking. It was a few years ago, but I think I left the SeaFoam in for a couple hundred miles (or whatever the directions said). So far, so good!

alx

DennisG01

I'm surprised low oil pressure won't cause that. Now, I say that without actually knowing one way or the other. Just that in some vehicles, depending on the computer programming, it does go into limp mode for low oil pressure. But again, I don't know with 100% certainty - just making an assumption based on other brands.

jonathankreb

So here is a quick follow up: After unplugging the sensor and then re-plugging it in, I went on the mother-of-all-road trips. Drove 4500 miles in 18 days. Most of the driving was on the highway at 70-75 mpg for many hours at a time--circumstances which, in the past, usually resulted in several false "check oil" messages. I went several days without getting the message, so it appeared that the root of my problem may have been a flaky electrical connection. I did get the false error message one time. After that, I unplugged the sensor, and scrubbed the contacts, then replugged. Drove another ~3000 miles without any additional false reports, so at least for me (knock on wood), the solution seems to be extremely simple.

DennisG01

Well that sounds promising! When you get a chance, put a little bit of dielectric grease on the contacts - not too much - dielectric actually inhibits electricity flow. But a small amount on the contacts... when you push the connector on, it will scrape away just where it needs to. If you want to up your game - get some Tef-Gel. I use that in the marine industry - fantastic stuff. With the dielectric... you could, however, smear a good amount around the connector body before snapping them together to further help insulate the waterproof connector.

hurricanewillis

I had the same type of issue with a 2009 GL320 Bluetec. For the past year, oil consumption has been high, but no oil leaks. Checked dip stick, took it to the dealer, mentioned my concerns, and they told me it was perfectly normal. 6 months later, I hear some sort of ticking noise coming from under the hood. Pop the hood, listen, can't really spot the noise, on my way to the dealer for an oil change anyhow. Hop on the freeway, ticking noise turns to banging noise, and boom, smoke and oil everywhere. I threw a rod it penetrated the block. 142,000 miles, and done. This just happened to me 8 days ago. Dealer wants $18,000.00 to replace the engine.

eric_in_sd

FFFFFFFFUUUUUUUU -

And I have an oil consumption problem that appears to have magically fixed itself. My heart goes out to you.

I imagine you can get a used motor for much less. My tranny went boom boom and I got a rebuilt installed for about 2/3 of the cost of new. There are options.

dwooderson

I might have to try that. We have been getting the false message on longish trips for years now, and we just ignore it. I'm reluctant to try to service this so close to my car's departure date (departing my ownership), but if it's this simple, maybe it's worth the effort.

Sonya Lyons

Is this a defect? Does anyone know what causes this?