'Engine Oil Low' check control message

[bissellh]

I am getting an 'Engine Oil Low' check control message on the dash of my 1992 BMW 525i E34 M50 non-vanos. I was getting it at idle and when I turned off the engine when the oil level in my engine was half way between the fill and full mark. After toppiing off the oil level to the full mark, I only get it when I turn off the engine. I just swapped this 78,XXX mile salvage engine into my car after my girlfriend blew up my previous engine. However, the message did not occur immediately after the engine swap. It started about 500 miles after the engine swap.

I do not know if this message indicates low oil level or low oil pressure. I read a lot of archives about low oil pressure. If it is low pressure I am prepared to remove the oil pan and work it out. If it is just a low oil level message I will pull the oil level sensor off the bottom of the oil pan during my next oil change to clean or replace. Does the message I am getting indicate low oil level or low oil pressure???

I will soon be doing a complete BG 44K intake and fuel clean on this engine because it was sitting stagnent for at least a year in the salvage yard. I imagine there may be some oil sludge in it. I think I read someting in the archive about running ATF in engine momentarily to clean the engine out. Can anyone recommend a way for me to clean the oil chambers in my engine at the same time I do the BG 44K intake and fuel cleaning???

[DaveVoorhis]

The sensor is used to check the oil level before the engine is started and just after it is stopped. The sensor may be sludged up but it's worth checking and cleaning the electrical contacts on the sensor and leads.

[Ross]

This indicates oil level as it says. There is a seperate warning for low pressure that says "low oil pressure".
The sensor may be sticky or failing.
The addition of an additive like Seafoam with a fresh oil change may free things up after a few changes. My opinion is to avoid the solvent flushing machines offered by some shops.
A fuel additive such as Techron will clean the fuel injectors.

[bissellh]

I cleaned the oil level sender and the electrical contacts. That did not resolve the problem though aven after disconnecting and reconnecting the battery. I replaced it with a used one and initially still got the same check control message. But, after disconnecting and reconnecting the battery, the problem went away.

Thanks for the responses!

[bissellh]

The check control module on my dash is STILL displaying that the oil level is low in my 1992 BMW 525i E34 M50 eventhough the engine oil is full.

This started happening after the engine overheated badly and destroyed my engine. I replaced the engine with a 80K salvage engine and that is when I started to get this message. The first thing I did was replace the oil level sensor with a used one and clean the contacts. That did not seem to help. Next I replaced the connector on the engine wiring harness to the oil level sensor because it seemed to melted and damaged. That did not seem to help either.

Disconnecting the battery resets the warning, but not for long. After reconnecting the battery and starting the car, I get the gong and message again after about 5 seconds of idling the engine.

There are three wires to the oil level sensor. I imagine one is power, one is ground and the other is a signal back to the computer and/or the check control module. I would like to test the oil level sensor. Does ayone have the pinout information for the oil level sensor plug and a way of testing it? I imagine I just ground the ground pin, supply 12V to the power pin and read the signal pin.

If that checks out, does anyone know how I can check continuity of the wires through the engine wiring harness back to the other end of the three wires?

[Kalevera]

There are three wires to the oil level sensor. I imagine one is power, one is ground and the other is a signal back to the computer and/or the check control module. I would like to test the oil level sensor. Does ayone have the pinout information for the oil level sensor plug and a way of testing it? I imagine I just ground the ground pin, supply 12V to the power pin and read the signal pin.

If that checks out, does anyone know how I can check continuity of the wires through the engine wiring harness back to the other end of the three wires?


It's a much more simplistic switch than that: it is switched to ground across two different level sensors -- oil level sufficient and oil level low. Brown is ground, the other two (don't remember the colors at the moment, blue and something, have a look at the ETM) are for the corresponding sensors. I would check continuity from ground (at the CHASSIS, not the engine), through the point where these pins come off of the engine harness and meet the body harness. That point is in X20, the 25 pin barrel connector to the rear of the diagnostic connector and proximal to the firewall/B+/aux & heater valve. If memory serves, male pin side is body, female is engine. On M50 525 cars, pins 1 and 2 in X20 route from the level sender to the CCM. Obviously, one pin is always continuous with ground. I don't remember which is which at the moment, so you'll have to look it up. I don't know for fact that this is the case, but if the engine wiring harness is burnt and both pins have bad or inconsistent ground, I wouldn't be surprised if it were CC module's behavoir to declare a low oil status. If no apparent problem with the switch: check it out by unlocking the connector, removing both pins and seeing what happens with the error message.

[bissellh]

Thanks for the help! I am not very knowledgable about the electrical, but I am trying to make sense out of this.

First, how do I test my oil level sender independently so I can eliminate that possibility from the equation?

Once the oil level sender is proven to work, it sounds to me like I should test continuity between the oil level sender connector wires and the corresponding pins where the engine wiring harness connects to the body harness that route to the CCM.

I am familiar with the 20 pin diagnostic port of my wiring harness from when I grounded pin 7 in order to reset my oil change and service lights on my CCM. Is the same place where I should check continuity of the wires from the oil level sender connector?

By the way, the color of the three wires in the connector to my oil level sender are:
1. blue/ yellow
2. dark brown/ light brown
3. blue white

[GoldenOne]

Heh, sounds soo familar....I replaced my engine with a used one with 75xxx on the clock when the spark plug failed in my e34 and I have a similar problem where i get the "low oil level" message even though the mark is showing half full. The only twist is that I am actually losing oil somewhere. Theres no oil in the coolant, I replaced all gaskets possible aside from headgasket, it doesnt appear that im burning oil because im not smoking nor is there excessive amounts of soot in the tailpipe. You wouldnt happen to have the same symptoms?

[bissellh]

I had a slow oil leak too. I think the mechanic who swapped the engines also swapped the oil pans and reused the oil pan gasket. I replaced the oil pan gasket with a new one and the dip stick tube O-ring. Man, was that job tough the first time around. Now, I have a faster oil leak than before. I have to put in a half quart for every tank of gas. Unlike your problem, I know where the oil is going. It leaks very bad onto the ground when the engine is hot. I have not looked to see where it is coming from yet. Your problem seems a bit mysterious to me.

Stay tuned on the oil level sender problem. I bet the mechanics either broke a wire in the engine wiring harness or forgot to ground a wire when they did the engine swaps.

[bissellh]

I have posted the same thread on bimmerboard. I just got a response about the wiries melting if the mechanic forgot to reconnect a ground wire on the starter. Here is the link: http://www.bimmerboard.com/forums/posts/369522

[bissellh]

I guess what you are saying is that if there were bad wiring between the sensor and the CCM the error message would be LOW OIL LEVEL instead of OIL LEVEL SENSOR. That is a little different from what I heard from kfister on bimmer board: http://www.bimmerboard.com/forums/posts/369610. He seems to think that the error message would be OIL LEVEL SENSOR if there were no connectvity between the chasis and pins 1 and 2 on the barrel connector.

I just went out to test connectivity between the chasis and pins 1 and 2 on the barrel connector only to find out there is none. I noticed that the error messgae on my CCM changed from LOW OIL LEVEL to OIL LEVEL SENSOR when I disconnected the barrel connector, which seems to follow what kfister advised.

I did have connectivity from the chasis to the lift hook on the engine which seems to suggest that the engine is sufficiantly grounded. Like I said before, I am not very good at electrical stuff. What is your take on this?