[bimmerbennn]

Hello,

I have an 07 335i N54 w/ 183k miles and FBO just about. I also run a JB4 piggy back. Oil level sensor reads inactive and water pump will continuously run when key is in accessory mode and slightly longer after the car is turned off (than it should be it seems). I have been daily driving this car for over a year now and this has been a problem, but finally trying to solve it. I have done quite a lot of research and done a few things which I will explain. I am hoping someone can lead me in the right direction.

What I have done:
I have replaced water pump & thermostat, oil level sensor, and alternator & battery (coded and registered) with all new OEM parts from FCP Euro within the last 2k miles. I know the last thing is this system is the IBS (Intelligent Battery Sensor). I have only one code that I believe is related which is 2E7C - BSD Data Bus Communication Fault. Attached are screenshots of other codes that the car has from Carly and MHD.

I followed a well done YouTube video where the guy went through the alternator wire with an oscilloscope look for a square wave and unplugged each of the 4 components one by one with key in and water pump continuoslly running (like mine). The alternator and oil level sensor were unplugged first and it did nothing but when the IBS was unplugged he got the square wave and the water pump turned off. In his situation the IBS was at fault. Mine does not do that until you unplug the water pump itself.

I have tested the fuses on the power distribution box located on top of the battery and they are good. Wiring at oil level sensor looks good. I had to recrimp a new water pump plug on as the previous owner cut it to run a different pump I believe and contacts were melted on the original connector, so I replaced it along with the pump. Those connections are good, but possibly an issue as its not OEM wiring completely? The pump runs fine and keeps the engine around 210-230 with regular driving. The car still runs and drives great.

I plan on testing fuses tomorrow and seeing if the water pump will run when I pull them out. If so, the pump would always be getting power which shouldn’t be right. Link to similar issue.

I also have an airbag and seatbelt light due to 93B2 - Battery Safety Terminal. Would this have anything to do with it?

I feel that it has to be some type of wiring or electrical issue.

Possible Solutions:

• Swap IBS (on order)
• Swap Voltage Regulator on back of alternator (link to similar issue)
• Get DME recoded/replaced

If you have any suggestions, please let me know. Hopefully this can help someone in the future with similar issues. I will update this when I figure more stuff out.

[bimmerbennn]

Following up…

IBS was replaced with new OEM from FCP Euro and codes were cleared. Did not remove the code.

Pin 13 on the DME in X05 section was loose upon inspection. Removed and opened DME and checked for continuity on pin 13 which it had. I bridged pin 12 and 13 with solder on the board because that pin is not being used for my DME (MSD80). There is a couple forums about it. Overall not too difficult. Just have to pop the tabs open, confirm pins 12 and 13, and carefully solder without touching the board. Also depinned and move the wire over 1 slot. This did not solve my problem and code still appeared.

I also checked DME relay for actuation when powering the car on and could feel it click on.

I have been driving the car around still with no issues besides not reading oil level and water pump staying on for longer than it should be, but always cutting off after a minute or so of turning the car off. I got a code 2ACB DME master relay activation. Which is weird because it seems to be working. I may replace just as a precaution.

Moving forward…

I will probably check all grounds on engine and harness, wiring around oil level sensor (cut back the corogated tube), and wiring on water pump again and track it back to DME. I will also ohm out my oil level sensor and compare to my old one if I can find it. I also may go and get my alternator tested just to make sure no diodes or anything is bad (may have to swap voltage regulator located on the back).

If anyone has any other suggestions, I would greatly appreciate any feedback on solving the 2E7C code and gaining access to my oil level.

[Hoody007]

I wonder if the water pump in your car isn’t the correct one.

Going through a similar issue my my newly purchased N55. Had the BMW dealer who sold the car change the level sensor as they were also doing an oil change, and the sensor they’ve been trying to install has been taking down the BSD bus.

Long story, and infuriating to say the least, but the part number on my old level sensor doesn’t match the new one they’re installing (part numbers are interchangeable and not superseded).

Symptoms mirror yours, except the BSD bus comes back when they unplug the level sensor.

Sounds like the water pump is your root cause, unfortunately. Is it an OE/OEM pump?

[bimmerbennn]

Originally Posted by Hoody007

I wonder if the water pump in your car isn’t the correct one.

Going through a similar issue my my newly purchased N55. Had the BMW dealer who sold the car change the level sensor as they were also doing an oil change, and the sensor they’ve been trying to install has been taking down the BSD bus.

Long story, and infuriating to say the least, but the part number on my old level sensor doesn’t match the new one they’re installing (part numbers are interchangeable and not superseded).

Symptoms mirror yours, except the BSD bus comes back when they unplug the level sensor.

Sounds like the water pump is your root cause, unfortunately. Is it an OE/OEM pump?

I bought an OEM pump from FCP Euro so it should be correct. I have lifetime warranty on it so it shouldn’t be a problem if I do have to replace it. The pump only has a couple thousand miles, but the owner before me cut the harness which I have redone. I followed a wiring diagram and the connections should be correct, but I can check them again. I have a feeling it may be a wiring issue with a broken wire somewhere.

I also have the original level sensor which I will compare when I get the chance to the new one that has been installed. It has had this problem since I have owned the car as I bought it as a non-runner. I have tried unplugging the alternator, IBS, and oil level sensor one by one to see if the pump would cut off with the key in accessory and it does not. Also clearing the codes in between does not remove the fault.

Thanks for your response. I will update when I get around to diagnosing more. Hoody007

[StradaRedlands]

bimmerbennn I wonder why PO cut the plug out? Maybe they were having similar problems and decided to go nuclear?

[bimmerbennn]

Originally Posted by StradaRedlands

bimmerbennn I wonder why PO cut the plug out? Maybe they were having similar problems and decided to go nuclear?

StradaRedlands I believe he put in one of those aftermarket racing pumps in at one point. I have it laying around somewhere and I vaguely remember removing wires going in through the passenger door. It was a sketchy setup, which is why I went back to factory. Now thinking back makes me wonder what wires he may of damaged doing the install.

[StradaRedlands]

Originally Posted by bimmerbennn

StradaRedlands I believe he put in one of those aftermarket racing pumps in at one point. I have it laying around somewhere and I vaguely remember removing wires going in through the passenger door. It was a sketchy setup, which is why I went back to factory. Now thinking back makes me wonder what wires he may of damaged doing the install.

Better than naught chance the problem lies within that wire harness!

[bimmerbennn]

Finally got around to working on this thing again, still been dailying the car.

Today I checked the oil level sensor wiring underneath. Everything was tight and no tears in the wire. Was not able to check the whole harness. I ohmed out the old oil level sensor: 121k ohms. I also tested the new one which has been in the car for a few thousand miles: 121k ohms (still installed on car when tested). I would guess both are good, but I have not looked for any specs on it yet. Engine to chassis ground on the drivers side was also OK. I tested the DME main relay and worked as intended. I also moved the water pump ground from the sway bar bolt to the engine, just to eliminate any chances, but no luck. Oil level inactive and water pump still runs unusually long after turning the car is turned off, but cuts out after a minute or so.

All I can think to do next is maybe get the alternator tested for bad diodes. Other than that, a new harness. Basically out of ideas unless the oil level sensor is bad?

[digitalashley]

Hey have you had any updates with this issue I have a similar issue. But without any error codes. And my pump kicks on just like yours but I find mine runs for a lot longer like yo 30 mins sometimes. Until I assume IBS system detects drain? And shuts power off completely? ..

[lefortez]

having a exACT SAme issue here. e93 335i n54. lately have a Increase battery discharge fault on my dash. changed the 2 year old battery as a preventive maintenance thinking it was that but to no avail. swapped IBS, water pump from a known good car and oil level sensor and still having BSD issue and increase battery discharge on my dash even with the new battery registered.

[bimmerbennn]

lefortez Yeah I still have this issue and daily drive the car. My battery is new and I have had no issues with it. Car sat for 2-3 weeks and started up without a jump/charge. My next step is probably the engine wiring harness. Maybe you have an alternator issue?

[bimmerbennn]

digitalashley I have made no progress since my last post on this issue. It hasn’t prevented me from driving the car. If I drive the car hard and get it the oil temp up to 240-250F, the pump will run for 20+ minutes. Also just bringing the keys near the car or opening a door sometimes will trigger the water pump even if the car is cold. I suspect the engine harness because it is almost like when something powers on in the car (lights, dash, etc.) the pump powers on as if it has a direct power source connection to the ignition/databus. Maybe? I really don’t know. I always have these engines codes:

• 2ACB DME master relay, activation
• 2E7C BSD data bus Communication fault

[skipraetor]

Same 2E7C CAN Bus fault and battery drain issue. Fwiw, the new water pump is not OE/OEM. New IBS installed today but after reading above it sounds like that isn't the issue. Battery is new, alternator is new. Just installed a new ground strap.

ProTool and multimeter shows 13.8 to the battery at start up, however, when the car is warm (above 240F oil temp) it drops to somewhere between 11.3 and 12.5v, typically 11.5v.

Protool reads no voltage at the water pump but it also says 14v to the battery "according to the IBS", and that measurement is with the IBS connected or disconnected. Oh yeah, new final stage resistor and Kl 30 relay as well. Yes, I've been chasing this ghost for a while. Thank you to the OP and all the replies.

*Update* after driving around more and initially getting 13.8v at the battery but only 11.5v once she's at operating temp, my theory is that the water pump draws too much current and there's something goes amiss with the DME once a water pump needs to be replaced and stays amiss if replaced with OE or aftermarket brands.

Full ISTA diagnostic on the CAN system with the power supply will be done within the week and I'll get back to y'all with the results.

[skipraetor]

Follow up: ISTA merely recommends the CAN Bus fault procedure of disconnecting each component and checking for a return of the code. I've coded out the RDC / TMPS but I have yet to disconnect the water pump and alternator to conduct step one (checking for a bad oil level sensor).

The more important update is that the voltage drop to the battery appears to only occur when going above 4k RPM. I had read a thread about poorly insulated Delphi ignition coils and the voltage drop under high loads, but I installed OEM Bosch last year, not Delphi. https://www.e90post.com/forums/showt...1428829&page=5

The odd part is that the voltage returns to 13.8 in some situations and other times it stays down and continues to drain the battery. I'd say 80% of the time the drop is permanent until the car cools down.

Is it time for a new set of coils? Or maybe a bad ground that I recently fixed had damaged the voltage regulator and that simply needs to be replaced.

[skipraetor]

Guessing the new alternator is bad. Swapped a new voltage regulator and the problem got worse. RPM made no difference.

Replacement on order. I'll bench test the old one before installing the replacement.



Update. It was the alternator. Probably failed because of the poor ground.

[MyPocketsHurt]

Hey I just wanted to reply to you.

I have this exact same issue and the water pump has drained my battery to dead but I cannot start my car. Put a new battery in and nothing. Replaced starter as well and nothing. But I get “INACTIVE” code for my oil level sensors but it used to work just randomly went out and water pump constantly running same as yours. My alternator was replaced in July.

I tried jumping my car, grounding it etc and no avail with starting.
What do you think could be my issue and is this no start related to either of the water pump or oil level?

[bimmerbennn]

MyPocketsHurt
I have not had a no start issue though I have similar symptoms. The water pump will eventually turn off for me, but it will also turn on randomly when I walk near the car. Never stays on until the battery dies. I think I remember seeing a similar forum with your issue though. I haven’t resolved my issue, but daily the car still. My next step is the engine harness.

I would try and check all the things connected on that harness. Water pump, alternator, IBS, and oil level sensor. There is a way to test each one and unplugging one at a time. I can’t remember the exact procedure but should be able to find it online.

[MyPocketsHurt]

Originally Posted by bimmerbennn

MyPocketsHurt
I have not had a no start issue though I have similar symptoms. The water pump will eventually turn off for me, but it will also turn on randomly when I walk near the car. Never stays on until the battery dies. I think I remember seeing a similar forum with your issue though. I haven’t resolved my issue, but daily the car still. My next step is the engine harness.

I would try and check all the things connected on that harness. Water pump, alternator, IBS, and oil level sensor. There is a way to test each one and unplugging one at a time. I can’t remember the exact procedure but should be able to find it online.

If you are able to find that procedure that would be great. I disconnected my IBS as I have no way of getting under the car currently and still no start. Will try to test water pump and oil level when I can get underneath.

[bimmerbennn]

MyPocketsHurt

I think theres information in the original post. Check the video. Is the pump on while you have the key in accessory mode? I think you have to disconnect one a time until the pump turns off. It never worked for me though.

[MyPocketsHurt]

Originally Posted by bimmerbennn

MyPocketsHurt

I think theres information in the original post. Check the video. Is the pump on while you have the key in accessory mode? I think you have to disconnect one a time until the pump turns off. It never worked for me though.

It will turn on as soon as any door is opened and when car is shut off will run for long time afterwards.

[chalupa2000]

I'm a part of this club...main symptoms of inactive oil level and water pump as soon as ignition on. I've unplugged the battery ibs, oil level sensor and alternator wires and the water pump still continues to run with ignition on. I'm thinking it's time for new water pump?...please anyone jump in for thoughts!