Q: Oil Level Sensor

[BMWDriver]

Where's the damn thing ?

I checked my oil level: right in the middle of the two lines of the dipstick, engine cold. But the engine kept reporting ENGINE OIL LOW. What gives? Something wrong with the oil pump?

Added 250 ml, no change. Did some highway (about 2-3 hours to burn some more), added the remaining 750 ml, and finally M50B25 is happy. I'm sure I have a bit above the top line.

And if anyone could enlighten me as to how much oil lies between those two lines (how much oil to add to top it off), I would certainly appreciate the knowledge because my own experience is inconclusive and not necessarily thorough nor scientific.

[repenttokyo]

i had a similar issue with my M50 last week - while changing the oil I added 6 liters to the car but it wouldn't show more than about halfway between on the dipstick. No Engine Oil Low warning, however.

I added another half liter, oil mark didn't move. I then added the rest of the liter, for a total of 7 liters, and it shot up above the top mark to a certain degree.

Never seen this before with my car, which is normally very happy with 6 liters.

[BMWDriver]

Mmmm... perhaps some conduits need unclogging or something...

[shogun]

oil level sensor has 2 contacts


static contact
dynamic contact

In case the oil level is sufficient, the static contact is closed.
Via the ground signal the check control gets to know that the level is o.k.
The dynamic contact is open, the control voltage flows against ground.
In case the oil level goes under the dynamic switch point, a message comes.
That the oil flowing into the oil pan when engine is switched off does not delete the alarm, the fault is stored with terminal 30.
It will only be deleted, when the static contact reports a message/signal, that the engine oil is filled up to static level.

The wires to the static contact are also checked for wire problems.
After ignition is switched on, a oil level warning will come. After starting to drive, but latest after 20 seconds this warning will disappear.

The wires go thru the pipe in engine room together with the thick wire from alternator to B+ pole. Right next to the B+ pole is the connector for these wires, check there, maybe the connector is brittle/broken.
Plug wires we labelled here


http://www.bimmerboard.com/forums/posts/560991/

[BMWDriver]

Good pointers. Will have to investigate further.

[tim eh?]

I used to get the 'OIL LEVEL SENSOR' warning now and then, which I guess means something else than your message. On my motor at least the sensor wire runs around all the coolant pipes kind of like the crank position sensor. When I replaced the cps I paid a little attention to the wire not really expecting it to help but I haven't had an error message since.... suspect points I guess would be around the pipes where it could rub or I think my problem was actually where the wire meets the sensor at the oilpan. (?)

[shogun]

a crtical point is the plug connection at the oil pan, there it is hot and the plugs crumble into pieces when you touch them. So it can be very easy that internally they are already disconnected although not to be seen from the outside. I did not have the fitting plug on the sensor side, because they only sell you a complete sensor with plug. But I found the one from Bosch, see part number in link. Maybe in USA it might be difficult to get the Bosch plug. I asked a friend in Germany to send me some, because the same plug is also used at other spots in the engine room. Pic from a similar connection next to B-plus pole
http://www.bimmerboard.com/members/hairwithit/c-%20LABELLED%20PLUG.jpg