[MJ777LR]

Hi folks, so this has been bugging me for a while. For as long as I've had my 07 328i, the oil level reading in the cluster has always been at 'max'. I've never seen it show anything else. Problem is, the last few oil changes I've drained out less than 7 quarts of oil.

So for today's oil change, I put in 6 qts to begin with, and took the car for a drive, made sure it was warm, etc. Well, guess what, the oil level read at 'max' just the same. Gauge read 'OK'. Clearly something's amiss.

Could my oil level sensor be faulty? I thought those sensors had sensors to sense if the sensor itself wasn't working... so far no error codes have been registered... times like this I really wish that I had a proper dipstick, cos' to me 'OK' is not really an oil level...

Anyone else have this happen to them?

[Three_thirty_I]

Originally Posted by MJ777LR

Hi folks, so this has been bugging me for a while. For as long as I've had my 07 328i, the oil level reading in the cluster has always been at 'max'. I've never seen it show anything else. Problem is, the last few oil changes I've drained out less than 7 quarts of oil.

So for today's oil change, I put in 6 qts to begin with, and took the car for a drive, made sure it was warm, etc. Well, guess what, the oil level read at 'max' just the same. Gauge read 'OK'. Clearly something's amiss.

Could my oil level sensor be faulty? I thought those sensors had sensors to sense if the sensor itself wasn't working... so far no error codes have been registered... times like this I really wish that I had a proper dipstick, cos' to me 'OK' is not really an oil level...

Anyone else have this happen to them?

I can only think that the level part of the sensor is then faulty (it is still then monitoring the condition so that your CBS is updated). Mine did something very strange a few weeks ago - the level was sitting on max since I serviced it earlier this year and since I always check the oil level as a way to gauge when the engine is up to temperature I see the current level each time I drive the car, so would notice any changes. All of a sudden it showed that it was sitting on 50%! It seemed to have skipped 75% which made no sense! I drove the car a few times that day and it kept showing 50%, then later that night I took the car for a spirited drive with plenty of WOT and revs and all of a sudden the level jumped back to 100%! After some more driving it dropped down to 75% when it has now remained (which for the distance since service and the type of driving is fair).

Going to just keep an eye on mine for now, but I suspect a new level sensor is on the card at some point...

[Efthreeoh]

The sensor is not faulty. The sensor is quite simple and uses a concentric capacitance tube as the mechanism to determine the level of oil. The system does not work like a mechanical dipstick and doesn't take a direct physical measurement of the oil level. The sensor provides oil level data that is temperature dependent and uses numerous readings to determine the oil level using software in the ECU, so the behavior of the e-dipstick sensor is related to how the data is processed by the software code and not the electric/physical operation of the sensor. The system is designed to tell you when the engine has less than 6 quarts of oil in it. Any reading between 7 quarts and 6 quarts (i.e. the bargraph) is just an estimate; when the +1 notification comes up, add a quart of oil within the next 120 miles.

[Three_thirty_I]

Originally Posted by Efthreeoh

The sensor is not faulty. The sensor is quite simple and uses a concentric capacitance tube as the mechanism to determine the level of oil. The system does not work like a mechanical dipstick and doesn't take a direct physical measurement of the oil level. The sensor provides oil level data that is temperature dependent and uses numerous readings to determine the oil level using software in the ECU, so the behavior of the e-dipstick sensor is related to how the data is processed by the software code and not the electric/physical operation of the sensor. The system is designed to tell you when the engine has less than 6 quarts of oil in it. Any reading between 7 quarts and 6 quarts (i.e. the bargraph) is just an estimate; when the +1 notification comes up, add a quart of oil within the next 120 miles.

We have replied on a few threads regarding this together, and what you say is interesting of course, but does not make sense from what I have experienced since owning my car, which is over 3 years now.

As said above, I am always checking my oil level and it has NEVER fluctuated apart from when the oil level has actually dropped. And it has always dropped in 25% increments. When it finally gets to the minimum level and asks for +1 ltr and you have added oil, it does take a while to show max level. Usually it starts by showing 25%, and then a little while later it will either jump all the way to 100% or one of the lower level before finally showing max. And this has been the case always. For it to all of sudden act differently does not make sense!

Maybe as this sensor gets a bit older it is a bit less accurate or tends to fluctuate more, but after driving for a few minutes from cold start it would always show the current level and would stay there when checking a bit later on while driving (minutes or even an hour or so later on).

So if the sensor is not faulty, then why is it suddenly showing difference readings (the oil level IS supposed to be the level of oil between min and max)? The sensor then also measures the state of the oil (CBS) and indicates how long before the oil needs to be changed, right?

Can you elaborate a bit more? Not wanting to argue, just going according to my observations over the years with my car - most people don't even know how to get to the oil level reading or for that matter know how to reset their TPS etc...

[Efthreeoh]

Originally Posted by Three_thirty_I

We have replied on a few threads regarding this together, and what you say is interesting of course, but does not make sense from what I have experienced since owning my car, which is over 3 years now.

As said above, I am always checking my oil level and it has NEVER fluctuated apart from when the oil level has actually dropped. And it has always dropped in 25% increments. When it finally gets to the minimum level and asks for +1 ltr and you have added oil, it does take a while to show max level. Usually it starts by showing 25%, and then a little while later it will either jump all the way to 100% or one of the lower level before finally showing max. And this has been the case always. For it to all of sudden act differently does not make sense!

Maybe as this sensor gets a bit older it is a bit less accurate or tends to fluctuate more, but after driving for a few minutes from cold start it would always show the current level and would stay there when checking a bit later on while driving (minutes or even an hour or so later on).

So if the sensor is not faulty, then why is it suddenly showing difference readings (the oil level IS supposed to be the level of oil between min and max)? The sensor then also measures the state of the oil (CBS) and indicates how long before the oil needs to be changed, right?

Can you elaborate a bit more? Not wanting to argue, just going according to my observations over the years with my car - most people don't even know how to get to the oil level reading or for that matter know how to reset their TPS etc...

I'm going to post something soon regarding the CBS oil monitor system, so what I say below will make more sense once you read my future post.

I recently had an issue with the CBS oil monitor system, which lead me to believe my sensor was not working properly. I replaced the sensor as a DIY project. It didn't fix the problem. I went to the dealer to solve the issue and through that process; I confirmed with the shop Forman that the sensor rarely goes bad (it's just too simple a mechanism to break). If the sensor does go bad it won't provide a reading at all (the owner's manual states this) and an error code will show in the ECU. You need to understand the sensor is part of a system that uses software to interpret the data coming from the sensor. The software is not as steady-state as you would want to think it is.

[Three_thirty_I]

Originally Posted by Efthreeoh

I'm going to post something soon regarding the CBS oil monitor system, so what I say below will make more sense once you read my future post.

I recently had an issue with the CBS oil monitor system, which lead me to believe my sensor was not working properly. I replaced the sensor as a DIY project. It didn't fix the problem. I went to the dealer to solve the issue and through that process; I confirmed with the shop Forman that the sensor rarely goes bad (it's just too simple a mechanism to break). If the sensor does go bad it won't provide a reading at all (the owner's manual states this) and an error code will show in the ECU. You need to understand the sensor is part of a system that uses software to interpret the data coming from the sensor. The software is not as steady-state as you would want to think it is.

Thanks! Look forward to this!

Well, the software issue is something that came to mind when I read up about this with my oil level that was fluctuating so much, reason being, I had my software for engine maps changed not more than a week or so earlier, so is possible that something with the software was getting confused and then eventually settled again...

[MJ777LR]

Thanks guys for all the input, that's some interesting reading right there. I guess I'm still not sure if my oil level sensor is still showing me the 'correct' amount of oil that's in the sump. I did drive it more than 20 miles with that 6 quarts in there, just to give it time to adapt to the oil level, since some posts mention the level changing gradually over time.

I don't think I'll splurge on a new sensor until I can be sure it's not working right. After all, I drive enough that my oil changes average 3 to 4 months apart, so the oil doesn't stay in there too long.

Efthreeoh, I'd be interested to know as well what you have coming up!

[Three_thirty_I]

Originally Posted by MJ777LR

Thanks guys for all the input, that's some interesting reading right there. I guess I'm still not sure if my oil level sensor is still showing me the 'correct' amount of oil that's in the sump. I did drive it more than 20 miles with that 6 quarts in there, just to give it time to adapt to the oil level, since some posts mention the level changing gradually over time.

I don't think I'll splurge on a new sensor until I can be sure it's not working right. After all, I drive enough that my oil changes average 3 to 4 months apart, so the oil doesn't stay in there too long.

Efthreeoh, I'd be interested to know as well what you have coming up!

What concerns me is that without a physical dipstick one is reliant on this thing reporting the correct level! These engines (like any other engine and especially as they age) use some oil over time and it is important to know what the oil level is doing. You can't top it up like you would with a physical dipstick, but when it gets to as low as 25% you can for argument sake add half a quart or ltr so that it is 75% or at least between 50% and 100%, so not over or near minimum.

But, when changing oil, best is to drain (this is what I have concluded and am doing) the oil with the engine still warm/hot and with the car sitting as level as possible so that every bit of old oil drains out, and leave it for a decent amount of time to drain completely. Then it is safe to simple refill with the exact amount regardless of what the oil level sensor says.

[Efthreeoh]

Originally Posted by Three_thirty_I

Thanks! Look forward to this!

Well, the software issue is something that came to mind when I read up about this with my oil level that was fluctuating so much, reason being, I had my software for engine maps changed not more than a week or so earlier, so is possible that something with the software was getting confused and then eventually settled again...

I posted this:

http://www.e90post.com/forums/showthread.php?t=926864

[Efthreeoh]

Originally Posted by MJ777LR

Thanks guys for all the input, that's some interesting reading right there. I guess I'm still not sure if my oil level sensor is still showing me the 'correct' amount of oil that's in the sump. I did drive it more than 20 miles with that 6 quarts in there, just to give it time to adapt to the oil level, since some posts mention the level changing gradually over time.

I don't think I'll splurge on a new sensor until I can be sure it's not working right. After all, I drive enough that my oil changes average 3 to 4 months apart, so the oil doesn't stay in there too long.

Efthreeoh, I'd be interested to know as well what you have coming up!

I posted FYI...

[Three_thirty_I]

Originally Posted by Efthreeoh

I posted this:

http://www.e90post.com/forums/showthread.php?t=926864

Awesome, thanks!! Have opened and going to read through thoroughly a bit later on.