2007 BMW Z4 3.0i Starting Randomly, Interface EWS-DME 2F45 Code

[Spencer McDonald]

First post here, and it's a weird one! I've been beating my head into every wall I have for a month now!

I've been helping a friend with his 2007 BMW Z4 3.0i auto with a weird issue where it will not start, not even crank, when turning the key 80-90% of the time and the other 20-10% of the time it will turn on no problem. When it doesn't start, it shows all proper signs of life and I can hear the engine prime/wake up, but still, no crank.

Everything we've tried has not fixed it, and this is everything we've tried:

-New battery in the car
-Replacing the key battery (twice with 2 different working key batteries)
-Replacing the EWS with a programmed one from BMW and re-syncing it to the car properly with INPA and Tool32

There is a code that comes up that could have a lot of causes, and the code is, 2f45 Interface EWS-DME. After not being able to pinpoint what the issue was, we took it to a BMW repair shop to have them diagnose the issue. they told us that the EWS was bad and needed to be replaced, which is why we ended up buying one from BMW to replace it. At the BMW mechanic's shop, he re-synced the DME and EWS saying that it might work temporarily, but not forever, Which is exactly what happened. For about a week and a half, the car would start up just fine first try every time, but after that, it slowly got less consistent over time to the point where it was the same as before. This is when we bought the new EWS. After installing it and re-syncing it, it started right up every time, but we weren't convinced since it might just be doing the same thing as before and would stop working at any time. Which is exactly what happened yesterday and why I'm making this post. I have researched far and wide on the internet and can find no one who has had this same issue!

There are a couple of things that we have found on other forums to check and try to see if they will help, and I will be doing them soon:

-Checking all of the cable connections to the DME to make sure they are seated properly
-Triggering the voltage at the starter solenoid
-possibly buying a new antenna for the ignition switch in the car
-I found a kit to do an EWS delete but I am hesitant because it is 200 bucks and I'm not fully convinced it is the EWS since a new one fresh from the factory didn't fix it.

A couple of weird things that possibly seem to make it start more often:

-Hooking the car up to a battery charger/jumper (not a battery pack one but one that plugs into the wall) or hooking it up to another car. Both seem to help but because it is random, it is very hard to tell so take it with a grain of salt.
-Possibly leaving the key in the ignition on position for a little bit also seems to maybe do something, but same as before, it feels like coincidence when either of these methods do anything.

Open to everyone and Ill keep everyone up to date on what stuff I try and what ends up fixing it! Thanks to everyone who read this!

[JAS1169]

Your potential issues are way past my pay grade, with repairs being done and then slowly fading back to an on/off no start.

However, consider cross posting, your post (copy/paste) to: https://www.z4-forum.com/forum/index.php This is a mainly a UK Z4 forum. I can recall posting there that involved no starts which required the EWS delete. Cross posting there should double your odds of finding your answer.

[Spencer McDonald]

Ok, I will try posting it there as well!

[JAS1169]

Given your possible starting better when jumped by another car/battery charger I'd look at the ground strap as a possible problem. Yet, I'm guessing you'd have looked at this already.

[wdb]

Since it's an automatic can I assume you've tried the usual stuff? Brake pedal switch, neutral safety switch...

[Spencer McDonald]

Because of the EWS-related codes and stuff, I haven't tried either the brake or neutral safety switches. Although, yeah, it still could definitely be those. What would be the best ways to test those on a car like this? I'm more used to workin' on classic cars haha!

[Spencer McDonald]

I've tried staring the car in neutral to see if the safety switch went bad and still nothin, I've also tried pushing on the brakes and the brake lights still turn on, so from what I understand, both those safety switches are working.

[MarinerZ4C]

Have you solved this issue? I didn't see a mention of the ignition switch - has this been changed out? If not, you may want to try changing switch module (not the key cylinder, but the switch).

On our E85/E86 platform cars, the ignition switch passes power to several circuits directly, without an extra relay, and the switch can look good, but have enough wear to pass inadequate current. This can lead to a 'no-crank, no-start'. Last Summer I had a 'no-crank, no-start', and I replaced my ignition switch - this was at ca. 92K miles. I could tell it was not the first replacement, because factory paint dots on the screws had been disturbed. I have not had a problem starting since replacing the switch.

I see you have been down several roads on this, so it may not be the problem, but time and difficulty to replace are not bad, and the part is between $40 and $100 (the BMW one is $$$, of course).

[Spencer McDonald]

I have solved the issue!! You were right! After too many hours of diagnosing and reading wrong info from "professionals" It was the freakin ignition switch! 20 dollar amazon part and it's done! Can't thank you enough! I fixed it about 2 weeks ago but sorry for the late response! Thank you all again for the help!!