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Technical Topics iDrive, Nav, Phone, Audio, Video, Cameras, Electronics remote start issue on 2021 M340i

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      10-03-2020, 09:14 PM   #1
RoyB
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remote start issue on 2021 M340i

I am randomly getting a check engine light when I attempt remote start and it won’t start the car. This has happened both through the app and using the fob. It’s about 50% success rate at the moment. There’s 113 miles on the car and no tune. I read some posts where people lost their remote start after tuning.
The error code is U0100 which looks like a communication problem with pcm.

I will give the dealer a holler Monday... but has anyone else had this issue?
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      10-03-2020, 09:50 PM   #2
Laylo21
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yup happens to me from time to time. although its been going on 2 weeks now without the issue. engine light goes away after turning off and on.
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      10-04-2020, 10:22 PM   #3
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That definitely isn't normal. I have a 330i and it remote starts without any issues. No CEL either. Only time I couldn't was when my phone battery was very low (1% charge I believe).
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      10-06-2020, 09:13 AM   #4
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Yes, have the same issue with my MY21 M340i, with only 130miles on it. I took it to the dealer last week with the exact same code readout and they said its due to the front bottom air flaps that open/close (not the grill, but below grill behind the mesh on the right/left of the car). Apparently they get stuck.

They said there was a bulletin on this for the X3 series that had the same issue. They cleared the code and asked to keep them informed if it happens again.

Of course its happened 3 or 4 times since last week, all on Remote Start operations.
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      10-06-2020, 11:29 AM   #5
RoyB
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Quote:
Originally Posted by BLG19 View Post
Yes, have the same issue with my MY21 M340i, with only 130miles on it. I took it to the dealer last week with the exact same code readout and they said its due to the front bottom air flaps that open/close (not the grill, but below grill behind the mesh on the right/left of the car). Apparently they get stuck.

They said there was a bulletin on this for the X3 series that had the same issue. They cleared the code and asked to keep them informed if it happens again.

Of course its happened 3 or 4 times since last week, all on Remote Start operations.
I dropped mine off at the dealer this morning and they are looking into it.

I also asked the SA why the battery only shows partial charged on drive screen. He seemed thoroughly confused. I said it's a mild hybrid but it only shows the battery partially charged and maybe this has a bearing on the remote start. He said it's not a hybrid, only the 330e was a hybrid. I explained that it has a 48v system. We went out to the car to much of his amazement he learned something new. It's a little scary when the SA doesn't know that something as large has a mild hybrid exists on their cars.
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      10-06-2020, 12:23 PM   #6
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Quote:
Originally Posted by RoyB View Post
I dropped mine off at the dealer this morning and they are looking into it.

I also asked the SA why the battery only shows partial charged on drive screen. He seemed thoroughly confused. I said it's a mild hybrid but it only shows the battery partially charged and maybe this has a bearing on the remote start. He said it's not a hybrid, only the 330e was a hybrid. I explained that it has a 48v system. We went out to the car to much of his amazement he learned something new. It's a little scary when the SA doesn't know that something as large has a mild hybrid exists on their cars.
Exactly the reaction from my SA when I picked up my car. Told him about the 48V MH and he looked at me very confused. I even showed him the Moroney Sticker where it showed 48VMH. He had no clue it was on the MY21's.

I've watched the Energy Flow display when driving and the battery does fluctuate up and down quite a bit. I'm generally sitting at about half battery... You'll find it charges up pretty quickly when going down hills or when doing a lot of eco/comfort driving (not hitting the throttle hard). But when hitting the throttle hard, you'll see it drains the energy there pretty quick... even shows arrows for forward energy being provided by both Engine and 48V MH.
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      10-07-2020, 08:53 AM   #7
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The SA said that the error was communication with BCM, which I confirmed beforehand with my scan tool. They "updated the programming" of the BCM to the "newest file" and they said that should fix it.

I picked the car up yesterday and have remote started it about 5 times since. It has started every time without check engine light which is promising.
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      10-07-2020, 09:10 AM   #8
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Quote:
Originally Posted by RoyB View Post
The SA said that the error was communication with BCM, which I confirmed beforehand with my scan tool. They "updated the programming" of the BCM to the "newest file" and they said that should fix it.

I picked the car up yesterday and have remote started it about 5 times since. It has started every time without check engine light which is promising.
Thats good to know... Keep us updated if you have the problem again. I'll contact my SA and see if they can try the same fix.
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      10-15-2020, 01:13 PM   #9
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I just picked up a 2021 M340i and had the same exact issue with remote start. It worked fine for the first few tries, but upon my last one: the car failed to remote start and the check engine light stayed on for about 20 miles before clearing itself.

Anyone able to figure out what this issue is?

Edit: I only have 300 miles on the car, bone stock.

Last edited by 340iTCP94; 10-15-2020 at 01:13 PM.. Reason: New car, No mods
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      10-15-2020, 01:55 PM   #10
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Bone stock 2020 M330xi here with 5K miles. Remote start works every time with app and fob, no CEL.
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      10-15-2020, 03:58 PM   #11
RoyB
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Quote:
Originally Posted by 340iTCP94 View Post
I just picked up a 2021 M340i and had the same exact issue with remote start. It worked fine for the first few tries, but upon my last one: the car failed to remote start and the check engine light stayed on for about 20 miles before clearing itself.

Anyone able to figure out what this issue is?

Edit: I only have 300 miles on the car, bone stock.
Have them re-flash the BCM. I am happy to report that the my remote start has been fine ever since they did that.
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      10-29-2020, 08:43 AM   #12
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I have had a remote start issue on my 21 as well. One night I used the remote start while walking to the car. The car started up and shut down after less than a second... check engine light which went away next day.

I have about a 50% success rate with the remote start..

along with my bass cutting in and out occasionally...
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      10-29-2020, 12:24 PM   #13
RoyB
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See my response above. Mine has been working fine ever since they did the re-flash.
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      04-01-2021, 09:39 PM   #14
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I recently got the Carbahn tune on a MY20. Had to disconnect to negative terminal of the battery and pull the DME. Went back in and started just fine. No CEL. But! Now remote start doesn’t work. Using the fob, the lights flash six times instead of three and all the pumps make noise like it’s about to start. But then it just doesn’t crank and I get a canned response inside saying it’s a failure due to any of these (insert list here) problems. Would a disconnected battery (for three days) and a reflashed DME cause it to “disconnect” for lack of a better word from the BCM? I’ve also heard disconnecting the battery like I did can cause a rolling code issue but then I would expect the car to not talk to the fob at all. My bet is on the former. Can anyone confirm?

What also concerns me is I found a flash tune option from another tuner that has a checkbox highlighting “stock remote start” or something to that effect. As in, maybe they need to save a particular file off the eprom before reflashing and then add it back in. That makes me think the Carbahn time may have totally wiped out the remote start function, in which case, would require a flash back to stock because there’s no way they’ll be able to retrieve that data.

Bottom line. I just want to be informed and have a plan A and plan B once it goes to the dealer in case they have to reflash back to stock.
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