"Stop Engine Oilpress" Message at low RPM

[Bdc101]

I changed my oil yesterday, and today I drove my kids to school. The car drove fine until we pulled into the school lot (about 4-5 miles) and the red oil pressure light comes on and it says "STOP ENGINE OILPRESS." I stopped it immediately and checked the oil, and it was low but still on the dipstick, and couldn't find any leaks or signs of losing oil.


I drove to Napa just down the street and noticed that if I kept the revs above idle the lights and message would go away. I put a full quart in it and drove to work, but the behavior is exactly the same.



I found a few threads that show many people having this same problem for extended periods of time. Particularly this first one, which describes having the problem and it possibly being related to an aux fan problem (I also disconnected my aux fan yesterday and drove to work without it, without thinking):

https://xoutpost.com/bmw-sav-forums/...e-oil-lev.html


I just wanted to ping the brain trust -- I don't think there is any actual danger to the motor right now, right? Especially since I just drove over 10 miles without it seizing up or spinning a bearing.



My car has just rolled over 130k and I just changed the oil with 5w40 euro blend full synthetic and a Mann filter. The previous oil I had left in for 9 months and about 9,000 miles, but it was because of a lot of highway road trips and normally I change it after no more than 6,000, always using quality filters and euro blend full synthetics. I have had the car for almost 40,000 miles and seven years. I also replaced the CCV system 6 years/35k ago, and see a little sludge on the dipstick and oil cap but can't find any other sludge in the system. I don't know if these things are important, just wanting to point them out.



Any help is appreciated! I have been putting a lot of time and effort into keeping this car up over the past year, and I'll be really bummed if it's going to keel over on me.

[nick325xit 5spd]

Well, I'd start by reconnecting the aux fan. I don't really see how that's linked, unless they're saying that the engine overheats that much with it disconnected, but hey...

Next, I'd replace the oil pressure sensor.

If it persists, I'd be suspicious of the oil pump or another oiling problem. Are your revs dropping more than usual? Thicker oil might help if the issue is a weak oil pump.

I definitely would NOT be commuting in it until I figured out if it's actually oiling the engine properly or not. These engines will go some time with zero oil pressure under gentle conditions, but not that long.

[Bdc101]

Also note that I reinstalled the engine fan yesterday (the engine-driven fan) after leaving it off all winter like I always do. I also broke the radiator shroud and removed it yesterday, which is why I disconnected the aux fan connector. I wonder if I might have damaged the oil pressure sensor wire during that work? But even if I did, why would it only trip the low-oil-pressure alarm at idle speeds? Anything over even 1,000 rpm or so, the alarm light goes away.



I also should note that it gave me the "Check Engine Oil Level" message a couple of times as well.



Could either a faulty oil level sensor or oil pressure sensor be tripping BOTH the oil pressure and the oil level alarms?

[Bdc101]

Originally Posted by nick325xit 5spd

Well, I'd start by reconnecting the aux fan. I don't really see how that's linked, unless they're saying that the engine overheats that much with it disconnected, but hey...

Next, I'd replace the oil pressure sensor.

If it persists, I'd be suspicious of the oil pump or another oiling problem. Are your revs dropping more than usual? Thicker oil might help if the issue is a weak oil pump.

I definitely would NOT be commuting in it until I figured out if it's actually oiling the engine properly or not. These engines will go some time with zero oil pressure under gentle conditions, but not that long.

Definitely no change in the behavior of the engine at all. I reconnected the aux fan, but forgot to reset the code with my foxwell (not sure if it resets itself after it faults). I will do that before I start it next.

[nick325xit 5spd]

Originally Posted by Bdc101

Also note that I reinstalled the engine fan yesterday (the engine-driven fan) after leaving it off all winter like I always do. I also broke the radiator shroud and removed it yesterday, which is why I disconnected the aux fan connector. I wonder if I might have damaged the oil pressure sensor wire during that work? But even if I did, why would it only trip the low-oil-pressure alarm at idle speeds? Anything over even 1,000 rpm or so, the alarm light goes away.

Idle is when your pressure drops the lowest. The BMW sensors are set real low, so if they're working properly and they go off, you basically have no oil flow.

I also should note that it gave me the "Check Engine Oil Level" message a couple of times as well.

Could either a faulty oil level sensor or oil pressure sensor be tripping BOTH the oil pressure and the oil level alarms?

They're totally separate sensors, so I wouldn't expect them to interfere that way. They also work completely differently. The oil pressure sensor is just a switch.

The only way that I would feel at all good about driving through this is if I hooked up an oil pressure gauge and confirmed that pressure is actually good. But it's probably less work to just change the warning sensor and see if that solves the problem.

[Bdc101]

Originally Posted by nick325xit 5spd

Idle is when your pressure drops the lowest. The BMW sensors are set real low, so if they're working properly and they go off, you basically have no oil flow.

I agree, that is why it seems like it can't be a broken or unplugged sensor. Perhaps it could be something like the sensor is plugged up with gunk, but why would that happen all of a sudden?

They're totally separate sensors, so I wouldn't expect them to interfere that way. They also work completely differently. The oil pressure sensor is just a switch.

Also agreed, but then why did I not get a low oil level light until after the car had warmed up and was throwing low oil pressure codes? (Especially since the oil is all the way to the top of the normal range on the dipstick.) The two problems have to be related.



One thing I was wondering, I made sure the big rubber O-ring on the oil filter housing is installed, but could the little O-ring in the middle cause oil to pool in the housing or something?I also used this Mann filter part number which I believe I've used before. If they sent me the wrong oil filter could it cause this problem? P/N 11427512300



I am trying to think how something could cause both of these problems at once here. Low oil pressure isn't something that could cause a low oil level at the same time, unless the engine was out of oil, which it's not.

[andrewwynn]

$25-30 I picked up oil pressure gauge to be able to confirm. On e70 I can read oil pressure through obd but I don't think that's possible with e53.

[nick325xit 5spd]

Originally Posted by Bdc101

I agree, that is why it seems like it can't be a broken or unplugged sensor. Perhaps it could be something like the sensor is plugged up with gunk, but why would that happen all of a sudden?

Plugged up or just slightly less sensitive.

Also agreed, but then why did I not get a low oil level light until after the car had warmed up and was throwing low oil pressure codes? (Especially since the oil is all the way to the top of the normal range on the dipstick.) The two problems have to be related.

Oil pressure is generally MUCH higher with cold engine (cold oil). It's not just a couple psi. If it throws the error cold, then your oil pump has lost prime and probably needs to be replaced.

One thing I was wondering, I made sure the big rubber O-ring on the oil filter housing is installed, but could the little O-ring in the middle cause oil to pool in the housing or something?I also used this Mann filter part number which I believe I've used before. If they sent me the wrong oil filter could it cause this problem? P/N 11427512300

I am trying to think how something could cause both of these problems at once here. Low oil pressure isn't something that could cause a low oil level at the same time, unless the engine was out of oil, which it's not.

I would replace the sensor and then report back. The range of possible causes for this issue are too wide to address without figuring out if the sensor is working.

[andrewwynn]

Oil pressure gauge prob less $ and you will have for future testing. I think I had to unplug the go-nogo sensor on wife's n63 motor to measure

[Clavurion]

Originally Posted by Bdc101

One thing I was wondering, I made sure the big rubber O-ring on the oil filter housing is installed, but could the little O-ring in the middle cause oil to pool in the housing or something?

Check those o-rings. If one of them has failed part of the oil pressure is lost directly back to sump.