[toksis]

My sensor reading going to half when doing long drive. When just normal it goes back to full. Some times it says 75 percent full and now it is full.

Is this a normal thing or need to change it? Thanks,

 

[Autoputzer]

Yes, as they get older they start giving false readings. My E46 M3 had both an oil level sensor and a dipstick. I'd get a low oil warning when the actual level measured by the dipstick was halfway between MIN and MAX.

If you do your own oil changes, you can do an electronic measurement just before, and then physically measure how much oil you drain out. From that, you can correlate the displayed oil level with the actual oil level.

 

[toksis]

so I guess need to replace it after testing. or maybe change it during change oi?

 

[Autoputzer]

The electronic oil level measurement on my two older BMW's read low. So, there was no danger of really having low oil and not getting a warning.

Rather than changing the sensors, I just topped off the oil with a 1/4 of a liter at a time. That'd make the warning go away for 1500 to 2000 miles.

 

[ard]

Q: How do you know when the oil level sensor fails?

A: Immediately after the red oil pressure light comes on and you ruin the motor, of course.