Yes another oil sensor issue

[sxychubles]

Backstory. Replaced oil sensor due to irregular readings.

Now it's saying to add one more quart. I've added 9 liters in total. Tried force resetting oil sensor and no luck. Thoughts?

[Scrippy]

So if your car is at operating temp, on a level surface, after 9 liters being added and it still recommends adding fluid after a BC oil reset? 2nd question is, under the above scenario how long do results take if you keep resetting?

[sxychubles]

Originally Posted by Scrippy

So if your car is at operating temp, on a level surface, after 9 liters being added and it still recommends adding fluid after a BC oil reset?

Correct. Went for a drive. One caveat I originally replaced the oil level sensor but then had to take out again to replace one of the studs, some of the oil did get into the connector. I did get out as much as possible and in my mind if it did cause electrical interference it wouldn't read at all.

2nd Q. I drove it around for 15min in 37C weather and it read. Parked it and reset through BC. At that point it read varied, between 30sec and 5min.

All at operating temp & level ground.

[Scrippy]

The time variation seems weird. Once I get one in, the next requests are all within 20-30 seconds. I would try electrical contact cleaner on both the connector and the plug portion of the sensor with a pan bellow for collection. Get any oil off and out of the contacts & connection points. No removal, just unplug, clean and let dry.

[nick3753]

Is the sensor aftermarket? I recall prior threads noting issues with them. In fact, I believe there was a recent thread with someone replacing multiple genuine bmw sensors as well.

[DrFerry]

Originally Posted by sxychubles

Backstory. Replaced oil sensor due to irregular readings. Now it's saying to add one more quart. I've added 9 liters in total. Tried force resetting oil sensor and no luck. Thoughts?

Give it sometime to recalibrate. It can take as many as up to 5 driving cycles for the reading to stabilize. At the moment you know the engine has enough oil in it (9L) even if the DME has not fully learned that fact yet. Try to do nothing to any of the system except for using the BC stalk to get a quick hot reading while driving and the car is at normal operating temperature. Do this for at least 5 longer driving cycles before worrying. Scroll through the BC stalk options until you get to the oil level option, and then hold the BC stalk button for 2 secs to engage the quick oil level read cycle. Do not add anymore oil.

[sxychubles]

Yeah def not adding any more oil. Cars back on stands, cleaning out the connection. If that doesn't work, I'll cycle through and if that doesn't work, lifetime warranty the sensor.

[sxychubles]

Originally Posted by nick3753

Is the sensor aftermarket? I recall prior threads noting issues with them. In fact, I believe there was a recent thread with someone replacing multiple genuine bmw sensors as well.

No no, this thing is getting all oem/oe parts. The sensor is genuine.

[sxychubles]

Car said no. Cleaner didn't help and resetting multiple times also didn't help.😭

[DrFerry]

Originally Posted by sxychubles

Car said no. Cleaner didn't help and resetting multiple times also didn't help.😭

Bad sensor? Not all new parts are perfect or the wiring loom is bad. Another idea is to disconnect the battery for 30 minutes and see if things return to normal when reconnecting. Why did you decide to replace the sensor in the first place? Could it be the wiring harness loom? Carefully check the wiring and insulation near the sensor connector.

[sxychubles]

Original sensor was giving me wonky readings..one day oil was full then next day it would read low. Figured it was time to swap it out.

[DrFerry]

Originally Posted by sxychubles

Original sensor was giving me wonky readings..one day oil was full then next day it would read low. Figured it was time to swap it out.

Here's a good thread on the sensor wiring:
https://www.m3post.com/forums/showthread.php?t=2212690
Some people try 3 sensors before getting a good one.

[sxychubles]

Love a good ol bmw quirk.

[Scrippy]

At this point I would be toning out the wires from the plug at oil sensor back to the DME connector with a multimeter. If there is no oil across signal or power wiring, I would suspect a shorted wire or two. Or like a few folks have said…..maybe the part is bad on arrival, which I have a hard time believing but we need answers.

[nick3753]

I second a battery disconnect trial first, easy enough to do. One of those old threads I mentioned had some success with disconnecting and reconnecting the alternator, but if I recal the sensor wasn’t reading at all, not just reading off. Odds are you’ll need a another new sensor.

[sxychubles]

Battery had been dead for a few weeks during the sensor replacement. I did disconnect it for 15-20min again. Drove today, once got a low oil warning and after a forced reset it wouldn't read. Car is back on all four jackstands.

Going to start tracing wires to dme. So far everything looks clean.

Here we go again!

[sxychubles]

Ok..update. replaced oil sensor. Same issue.

Full backstory.
On stands for a month. One month ago I did an oil change and got 8l out. Replaced oil sensor. Filled it up with 8. Noticed a bunch of leaking around oil filter housing and oil lines so I replaced oil filter housing and oil cooler lines. Drained oil after and got 9l of oil out, put 9back in. Off stands and drive around to try and reset the oil sensor.

Back on stands Today I drained it an it gave me 7.7l ( I forgot to warm up car before as I was rushing. ) I put 7.7 back in.

New Sensor reads still low. Thoughts, just low on oil?

No this isn't my first time working on cars but at this point I'm feeling a bit lost.

[DrFerry]

Originally Posted by sxychubles

Ok..update. replaced oil sensor. Same issue. Full backstory. On stands for a month. One month ago I did an oil change and got 8l out. Replaced oil sensor. Filled it up with 8. Noticed a bunch of leaking around oil filter housing and oil lines so I replaced oil filter housing and oil cooler lines. Drained oil after and got 9l of oil out, put 9back in. Off stands and drive around to try and reset the oil sensor. Back on stands Today I drained it an it gave me 7.7l ( I forgot to warm up car before as I was rushing. ) I put 7.7 back in. New Sensor reads still low. Thoughts, just low on oil? No this isn't my first time working on cars but at this point I'm feeling a bit lost.

With this new information we are back to this part -> Give it sometime to recalibrate. It can take as many as up to 5 driving cycles for the reading to stabilize. At the moment you know the engine has enough oil in it (9L) even if the DME has not fully learned that fact yet. Try to do nothing to any of the system except for using the BC stalk to get a quick hot reading while driving and the car is at normal operating temperature. Do this for at least 5 longer driving cycles before worrying. Scroll through the BC stalk options until you get to the oil level option, and then hold the BC stalk button for 2 secs to engage the quick oil level read cycle. Do not add anymore oil - yet. IF I'm following the math correctly - 7.7L are in the engine, and 1.3L are in the oil cooler, oil cooler lines, and oil filter housing (7.7L + 1.3L = 9L mentioned in an earlier post above). While waiting for the system to recalibrate I advise against red lining the car. Try to keep the RPMs below the 5400RPM break in rev limit recommendation until the system and sensor become calibrated and stable using the process described above. PS: Leaving the car for a month without being on a battery tender may have caused some issues with stored values (adaptations) within the DME memory.

[sxychubles]

Is driving it different than letting it idle on stands?

[sxychubles]

I had a million codes when the battery died, cleared all of them.

[DrFerry]

Originally Posted by sxychubles

Is driving it different than letting it idle on stands?

Yes, based upon the documentation provided below, there appears to be a difference in sampling rate between when the car is idling (~1 minute to get a reading) and when the car is being driven (up to 5 minutes to get a reading). See photos below:
.

[sxychubles]

Originally Posted by DrFerry

Yes, based upon the documentation provided below, there appears to be a difference in sampling rate between when the car is idling (~1 minute to get a reading) and when the car is being driven (up to 5 minutes to get a reading). See photos below:
.

Went for two drives yesterday. Sensor read once 4-5min after engine was at operating temp. Was not able to get a second reading after forcing it (waited about 6-7min). One thing I did notice was the previous sensor read a little sliver below the min mark where as this one shows nothing below the min mark. I think I'll add 300mil and see if it reads it, at this point I feel the car was low on oil due, somehow.