[Smok335]

Hey folks, new to the forum so thanks for adding me.

I just picked up a project from my family in Florida as they couldn't figure it out. 2007 E92 335i. It runs great just needs a bit of work. One of the reasons they sold it to me is that it was a water ingress somewhere that is causing problems that I am trying to figure out.

Started when they had it on a rainy day and the car simply shut off on the driver at the time. Has recently had a DME replaced (might be related to the water, but no way of knowing for sure). Fast forward to yesterday, was driving from Denver to Colorado Springs and had a light drizzle come down for maybe 10-15 minutes. I knew I shouldn't be driving in it, but had to get home and was interested to see if that small drizzle would cause a problem. Got my answer as soon as the rain stopped. Seems as if some water did find its way somewhere as I got a limp mode warning on the car. It is MHD stage 1, so while I did lose power, it wasn't debilitating to drive in the least. I drove it with that limp mode for maybe 20 minutes before pulling off and opening the hood to see if I noticed water anywhere.

Shut the car off, let it sit for 5 minutes and then it started back up perfectly. My guess is the heat of the engine evaporated whatever water was there during the 20 minutes I continued to drive and it was okay.

Current thoughts are:
That since it happened after the rain stopped, it's water from above and not road spray as the road was dry by then.
That since the DME did go bad recently, going to attribute that to the water problem.
That since the problem went away after a bit of driving (assuming heat from the motor evaporated it) that the problematic leak is in the engine compartment.
That since there was a tad bit of water in the carpeting (told to me by my dad before I bought it) that this leak is either one leak and finding it's way to some electronics or equally likely, two leaks and only one is actually hurting driving it.


Would love any suggestions or experiences people have had with problems similar to them and what the fix is. I live in Colorado and have a daily, so not driving when it's raining isn't that hard to do, but very inconvenient.

My current thought is the cowl drain by the DME box is leaking somehow causing it, but have also heard that a small bit of water by the vaccum pump sensor could cause limp mode and other problems, but I haven't noticed any odd vacuum pump related noises (this thing has had downpipes and exhaust mods, so it's loud and not sure I would really hear them).

I realize this is an odd one, and I tried to add as much description as possible to assist with that. If anyone thinks of a piece of info that could help and I haven't put it on this OP then please ask away, any help will be much appreciated.

Again, thanks for the add, and thanks in addition for the help!!

[StradaRedlands]

Cowl sounds like a good guess! Just throwing them out there, but maybe sunroof drains somehow getting the fuse box area wet. Could also be rear tail light by battery... that's a known problem. Sunroof drains and rear taillight seals are just things that happen a lot, so wanted to put them on your radar.

[Smok335]

Originally Posted by StradaRedlands

Cowl sounds like a good guess! Just throwing them out there, but maybe sunroof drains somehow getting the fuse box area wet. Could also be rear tail light by battery... that's a known problem. Sunroof drains and rear taillight seals are just things that happen a lot, so wanted to put them on your radar.

Awesome, I appreciate that and will definitely go check those spots. Sunroof drain I do think is good because the headliner shows no evidence of ever being wet, rear taillight will definitely be inspected!

Unfortunately I think I have something less common as I don't see alot of threads discussing water leaks and limp mode/ bad DME.

[lowrydr310]

Originally Posted by Smok335

Unfortunately I think I have something less common as I don't see alot of threads discussing water leaks and limp mode/ bad DME.

It's not common. (leaks that let water onto the passenger side footwell, that's a different story.) Pull that DME box lid and see if there's water.

Do you have any way to scan for BMW-specific codes? Not one of those generic OBDII readers. but if you get a proper setup for reading codes that will probably point you to the cause of the failure, at the very least it'll help you narrow your focus.

My wild guess is there's water getting into a sensor connector, or a module connector, but you won't know where to start looking until you can find the specific fault codes.

[Smok335]

Originally Posted by lowrydr310

It's not common. (leaks that let water onto the passenger side footwell, that's a different story.) Pull that DME box lid and see if there's water.

Do you have any way to scan for BMW-specific codes? Not one of those generic OBDII readers. but if you get a proper setup for reading codes that will probably point you to the cause of the failure, at the very least it'll help you narrow your focus.

My wild guess is there's water getting into a sensor connector, or a module connector, but you won't know where to start looking until you can find the specific fault codes.

I do have a full computer loaded with the ETK and everything on the way, will have to look into that further. I just got the Car last Thursday so haven't had too much time to actually work on it yet. Plan to pull the DME box lid this weekend and do a deep dive to try to find it, but figured I'd see if anyone could assist with some tips to check for.

Appreciate the help