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BMW False Low Oil Level Warning – Replace Oil Level Sending Unit Sensor

January 8, 2013

This answer is applicable for many BMWs in addition to the one listed below.

Q
car year: 2002 car model: 525i If the check engine oil lights comes on after changing oil and check the oil, will replacing oil sender level stop this or can it be reset and how easy is it to replace?

A
Most BMW models from the early ’80s on have some form of oil level sender/sensor that will generate a warning when the engine oil level goes below a given point.  These sending units do fail and they generate false low oil warnings.  If the low oil warning is on, but a physical check of the oil level (when a dip-stick is present) shows that the oil is full to the appropriate level, then it is likely that the sensor is faulty.  The sensors are typically mounted in the lower parts of the engine oil pan (the sump).  Some are mounted directly on the bottom and others are mounted at some point above the bottom of the oil pan.  The Bentley repair manual for a given model will detail the location of the oil level sending unit.  Once the faulty sending unit has been replaced, the false warning will be extinguished.

Replacement of the oil level sending unit is typically a simple procedure of disconnecting the electrical harness plug and removing two or three bolts or nuts and pulling the unit from the oil pan, then replacing with the new one (be sure to use a new sealing o-ring).  Since the sending unit is in the bottom of the oil pan, the oil does need to be drained first, so we would recommend that the replacement be done during a standard oil change.

Bentley repair manuals:

Oil level sending units (sensors)
(search “oil level” after clicking link):

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