Where do I find oil sending unit on a 2001 BMW 740il E 38.. My oil pressure i reading low pressure. But its full of oil..

Have you checked the actual pressure with a mechanical gauge? It could be a bad sending unit.

The oil level sensor is on the bottom of the oilpan held on by 3 10mm nuts. The oil pressure switch is on the remote oil filter housing,

It is attached to your oil pan, it is a flat sensor. Google "oil level sender E38" and select images, you will see what you are looking for.

Remove the oil pressure sending unit and have a test gauge hooked up and see if the sending unit is defective. If you really have low pressure the engine should be making lots of noises.

First make sure oil is full, this may be low oil pressure or bad oil sending unit, you should have this checked ASAP.

engine damage can occur due to low oil pressure, you need to have this checked, it may just be a bad sensor. (sending unit)

see this tips and fix it. God bless you
The oil pump supplies oil to lubricate your engine. If the oil pump is worn or is not turning, the engine will suffer a loss of oil pressure, which may result in engine damage or engine failure.
The first sign of trouble may be a low oil pressure warning light, a drop in the normal reading on you oil pressure gauge (if your car has one), or the appearance of ticking or clattering sounds from your engine.
As a rule, most engines only need about 10 PSI of oil pressure for every 1,000 RPM of engine speed. Oil pressure will read higher than normal when a cold engine is first started because the oil is thick. Oil pressure will gradually drop as the engine warms up and the oil thins out. So normal oil pressure on a warm engine cruising down the highway is typically 30 PSI up to 45 PSI.
SYMPTOMS OF OIL PUMP TROUBLE
The first thing you should do if any of these symptoms occur is to stop your car, turn off the engine, let it sit for a few minutes, then check the oil level on the dipstick. If the oil level is at or below the ADD line, add a quart of oil to bring the level back up to the full mark. Add as much oil as is needed to raise the level to the full mark. Then restart the engine. If the warning light remains on, or the oil pressure reading does not climb back up to its normal range, or the engine noise does not go away, you may have a bad oil pump.
The other possibilities include a bad oil pressure sending unit, or a problem with the oil pressure warning light circuit or oil pressure gauge.
OIL PRESSURE SENDING UNIT
If the engine is NOT making any unusual noises and seems to be running normally, and the oil level on the dipstick is FULL, but you are still getting a low oil pressure warning light or low gauge reading, the fault could be a bad oil pressure sending unit.
The oil pressure sending unit is mounted on the engine block. On some applications, there is a spring-loaded pressure-sensitive diaphragm with a switch inside the sending unit. This switch completes the circuit to the low oil pressure warning light if oil pressure drops below a certain threshold. The unit may stop working if the diaphragm inside fails, if the switch is stuck, if the small hole that allows oil to enter the sending unit becomes plugged, if there is a loose, corroded or broken wiring connector at the sending unit, or there is a fault in the wiring circuit between the sending unit and warming light.
On vehicles that have an oil pressure gauge (electronic, not mechanical), the oil pressure sending unit has a small rheostat inside that sends a variable voltage signal to the oil pressure gauge when the diaphragm moves. A worn spot on the rheostat or any of the other problems just described for the simple pressure-type oil pressure switches can cause a problem.
FORD'S FAKE OIL PRESSURE GAUGE
On many Ford vehicles that were built from 1980 through the 1990s, the oil pressure sending unit has two switches, a low pressure and a high pressure. These vehicles also have an oil pressure gauge, but the reading on the gauge is not a true indication of real oil pressure. As long as the pressure to the sending unit is between high and low, the gauge will read normal. If oil pressure drops and trips the low pressure switch, the dash gauge will now read low. Or, if oil pressure goes up and trips the high switch inside the sending unit, the dash gauge will read high. Consequently, don't rely on the oil pressure gauge for an accurate reading in these vehicles. It is only a gross indication if the oil pressure is low, normal or high.
OIL GAUGE PROBLEMS
If the engine is NOT making any unusual noises and seems to be running normally, the oil level on the dipstick is FULL, and you have replaced the oil pressure sending unit but are still getting a low oil pressure reading on the dash gauge, the fault could be in the wiring circuit between the sending unit and gauge, or the gauge itself might be bad.
Check the wiring connections on both ends as well as wiring continuity between the sending unit and gauge. If no wiring faults are found, hook up a pressure gauge directly to the oil pressure port on the engine and check oil pressure with the engine running. If the engine-mounted gauge shows normal oil pressure but the dash gauge is reading low, the problem is a bad dash gauge.
On the other hand, if the engine-mounted pressure gauge reads low and you have done all of the above, chances are the oil pump is worn, or it is not picking up enough oil because of a restriction or blockage in the pickup screen in the bottom of the crankcase.
OIL PUMP PICKUP PROBLEMS
The pickup tube has a screen on the end to prevent large chunks of anything bad that ends up in the crankcase from being sucked into the pump. But we are talking BIG chunks of debris, not normal wear particles or carbon or dust or other microscopic-sized abrasive particles that can cause pump wear over time.

Oil light should not come on unless the Level is LOW or the Oil Pressure has dropped below safe operating limits. I would do 3 things
1. Check Oil Level, if low, fill to the correct level and then restart.
a. if the light does not go out....
2. Pull the Oil Pressure Sending unit out and install a pressure gauge
a. if the pressure is in normal operating limits, chances are the Oil Pressure sending unit is bad
b. If the pressure is low, the issue is
1. Oil Pump
2. Engine Main or Rod bearings are bad and a engine rebuild is on its way

when the engine is cold the oil pressure should read 60 psi
when the engine warms up at operating temp. it should read 12-16 psi while running at speeds 40+ it should read about 38-42 psi.
it it reads all that its not you sending unit
remember its a GM they use the poorest oil pumps on the market. usually I won't see a pump going out untill over 100K or so. its the same frame as the suberben, yukon, tahoe,denali.
4WD will make the job 3 times harder. If you do have the job done ask for a high volume pump

The oil pressure sending unit has gone bad. I sending unit is just above the oil filter and you can get to it from the top. When you face the Engine look down towards the oil filter, the oil pressure sending unit is just above that and it looks like a cylinder with two wires coming from it. If you don't see it, it's right between the exhaust manifold and oil filter.
If you go to Auto Zone or Parts Source, they'll have the oil pressure sending unit and the step by step instructions, When installing the new sensor. Do not use teflon tape or any sealant, the sensor is tapered and need's the good ground from the engine to give you right readings.
Good luck and hope this helps.

the light is probably sending an OIL Pressure drop warning ---there is a rarity however
an oil filter may be improperly installed or the OIL Pressure connection on the oil pressure
sending unit --usually next to the filter --is loose or corroded or the oil pressure sending unit may
be going bad ---on a 2001 it is conceivable
otherwise you have an internal oil pressure leak --crank or cam bearings --bad o ringy thingy somewhere or the oil pump --may be experiencing problem too or the pick up screen in the oil pan
is somwhat clogged ---for a clog --try what's called SEAFOAM in the oil ---the stuff actually works
like it says on the can --about 8 bucks --drive for a week --say 500 miles worth and change the oil filter again --just the filter ---either way OIL Pressure is nothing to ignore ---you need to fix that
asap depending on the problem source!!!
I hope this helps
HAWK