[blakekald]

I replaced my thermostat and water pump a little over 2 years ago.

Around 6 months ago, I got a drivetrain malf. when leaving work at 3am. I read the code with MHD and it said my thermostat was clamped open. So I purchased a new one on FCP Euro and replaced it. After resetting the code the car drove fine for a couple of days. About a week later leaving work again at 3am, drivetrain malf. came up again and so did the code.

I pulled over and reset the code and the car drove fine.

I've noticed a trend that it happens once every 2-3 days, and it will only happen when I drive home from work at 3am. If I start the car any time during the day, no issues. Just when I start it at 3am leaving work its a 30-50% chance that it'll throw the code, but as long as I reset the code with MHD it drives perfectly fine.

I replaced the battery from BMW last week and it's still happening.

Anyone have any suggestions as to where I should start looking to narrow down the issue?

[F32Fleet]

Issue with the connector?

[n55david]

Is there an additional thermo at the trans cooler (if you have one) like the x3/x4?

On my x3 I had that one fail and it causes symptoms exactly like the one at the water pump since it's all part of the same system.

[harkes]

Seriously - who wants to get up 3am. I'd throw codes too if that was me

[ctt300]

Check your coolant level

[zinner]

Originally Posted by ctt300

Check your coolant level

on my F30 335i 2015, low coolant in the overflow tank will result in a low coolant error message, not drivetrain malf. FWIW

[blakekald]

Originally Posted by F32Fleet

Issue with the connector?

I've checked the wire and the connector of the coolant temp sensor and it looks like there is nothing wrong with it. I just got a new coolant temp sensor in, and I'll be replacing it this weekend. I seen a post on FB N55 group with someone who is having this EXACT same issue, and he replaced basically everything that has anything to do with the coolant and he's still having this issue.

Originally Posted by n55david

Is there an additional thermo at the trans cooler (if you have one) like the x3/x4?

On my x3 I had that one fail and it causes symptoms exactly like the one at the water pump since it's all part of the same system.

Yes, there is a transmission thermostat on the transmission cooler, and that will be replaced next if this coolant temp sensor does not fix the issue.

Originally Posted by harkes

Seriously - who wants to get up 3am. I'd throw codes too if that was me

I would hate to get up at 3am. I leave work at 3am lol. I get up at like 11am

Originally Posted by ctt300

Check your coolant level

I haven't really looked at my coolant level (and if its ever low I get a pretty in your face warning about it via the idrive), but is this really something that can cause the issue I'm having?

[F32_Sierra]

the most underrated troubleshooting with any car is looking up the manufacturer's code setting criteria for every code thrown. This will help you understand EXACTLY what the DME is seeing vs what it's looking for. This definitely will expedite any troubleshooting since you know what to look for.

[blakekald]

Originally Posted by F32_Sierra

the most underrated troubleshooting with any car is looking up the manufacturer's code setting criteria for every code thrown. This will help you understand EXACTLY what the DME is seeing vs what it's looking for. This definitely will expedite any troubleshooting since you know what to look for.

Me and my local shop have researched every code my car threw. I've read every forum post, BMW fault code look up, I even found a TSB for the main code I'm getting, and still to no avail.


Codes:
1D2008
10AA30
CF2DE2


Water pump replaced 2 years ago.

Thermostat was replaced 2 years ago as well, but I also replaced it when this issue first started happening around 10 months ago.

Coolant system has been flushed and pressure bled 4 times now. Not a single leak in the system.

The coolant/oil temperature sensor was replaced.

TSB for 1D2008 was followed and the thermostat for the transmission was also replaced.


After all of this I am still having the issue, and we can't seem to figure out what it could be.



****If someone is willing to point me in the right direction and is able to help me get this solved I am seriously willing to shoot them some cash.

[n55david]

Originally Posted by blakekald

Me and my local shop have researched every code my car threw. I've read every forum post, BMW fault code look up, I even found a TSB for the main code I'm getting, and still to no avail.


Codes:
1D2008
10AA30
CF2DE2


Water pump replaced 2 years ago.

Thermostat was replaced 2 years ago as well, but I also replaced it when this issue first started happening around 10 months ago.

Coolant system has been flushed and pressure bled 4 times now. Not a single leak in the system.

The coolant/oil temperature sensor was replaced.

TSB for 1D2008 was followed and the thermostat for the transmission was also replaced.


After all of this I am still having the issue, and we can't seem to figure out what it could be.



****If someone is willing to point me in the right direction and is able to help me get this solved I am seriously willing to shoot them some cash.

Trans cooler thermostat.. its a heat transfer block for the oil and coolant etc.. that thermostat can stick too.

[blakekald]

Originally Posted by n55david

Trans cooler thermostat.. its a heat transfer block for the oil and coolant etc.. that thermostat can stick too.

As mentioned in the post you quoted, the TSB that we followed had us replace the trans cooler thermostat, and the issue was not fixed.

Latest thing that we tried was swapping a completely different DME and the issue is still continuing.

[BeastMode335i]

Originally Posted by blakekald

As mentioned in the post you quoted, the TSB that we followed had us replace the trans cooler thermostat, and the issue was not fixed.

Latest thing that we tried was swapping a completely different DME and the issue is still continuing.

Woke up to oil in my coolant this morning, and ironically I'm throwing those exact 3 codes....

What was your fix?

[baceeddie]

Originally Posted by BeastMode335i

Woke up to oil in my coolant this morning, and ironically I'm throwing those exact 3 codes....

What was your fix?

Did you guys figure this out? I am having the same issue...

[Skrrtt335]

i've had this issue for about 3 years , it happens everytime its cold outside i just reset the code and it goes away . car warms up good & car drives fine . never replaced the thermostat . the code comes up as thermostat stuck open . dont really have an answer for your problem but it hasnt been a big issue for me . 2015 335 xdrive bm3 stage 2

[BeastMode335i]

Originally Posted by baceeddie

Did you guys figure this out? I am having the same issue...

Sure did! It was the oil heat exchanger under the coolant expansion reservoir.

[SpoolinAddict]

Originally Posted by BeastMode335i

Sure did! It was the oil heat exchanger under the coolant expansion reservoir.

can you tell us how much was the repair?

[BeastMode335i]

Originally Posted by SpoolinAddict

can you tell us how much was the repair?

Bout $200 I think.

[KingBehrens]

Originally Posted by BeastMode335i

Bout $200 I think.

I’m having the same issues, I’m kinda confused on how this would fix the issue. I heard that the oil and coolant will mix if that fails and I don’t have any mixing but I think it’s causing my issue too. Do you know if that might be my case?

[BeastMode335i]

Originally Posted by KingBehrens

I’m having the same issues, I’m kinda confused on how this would fix the issue. I heard that the oil and coolant will mix if that fails and I don’t have any mixing but I think it’s causing my issue too. Do you know if that might be my case?

Could you elaborate a bit more? What exact issue are you having, the codes being thrown, or the drivetrain malfunction?

[KingBehrens]

Originally Posted by BeastMode335i

Could you elaborate a bit more? What exact issue are you having, the codes being thrown, or the drivetrain malfunction?

Hey sorry, the thermostat code. I have replaced my coolant temp sensor, thermostat, and had a shop do my transmission cooler. Still having an open thermostat code. I just ordered the oil heat exchanger off fcp euro. I’m hoping this will solve my issue, otherwise I think it might be a DME issue. How difficult is the oil heat exchanger, or did you have a shop do it?

[OATMEEL]

Originally Posted by KingBehrens

Hey sorry, the thermostat code. I have replaced my coolant temp sensor, thermostat, and had a shop do my transmission cooler. Still having an open thermostat code. I just ordered the oil heat exchanger off fcp euro. I’m hoping this will solve my issue, otherwise I think it might be a DME issue. How difficult is the oil heat exchanger, or did you have a shop do it?

Keep me updated on this. I am having the same issue on my n20 x3 right now.

[KingBehrens]

Originally Posted by F25_x3

Keep me updated on this. I am having the same issue on my n20 x3 right now.

I will, hoping to get it done this Sunday as it’s supposed to be nice out. Might be a bit though since I’ll be doing the oil filter housing gaskets, the Mickey Mouse flange, cleaning out coolant reservoir, and changing out thermostats again just in case. But shouldn’t be too bad, I’ll definitely let you know if my problem ends up fixing itself after that