High pitched whine after DCT 1200 mile service

[Polarstar]

I Just had the 1200 mile service, and now my 2011 e90 M3 has an annoying high pitched whine when accelerating, starts at about 1500 rpms, increases until it (or I) shift(s), depending upon the mode, then continues through each gear. DCT transmission, happens in auto or "manual," with power button on or off, in m mode or not, and while revving in neutral. It didn't do this for first 1200 miles, and I can't think that changing the oil, oil filter or differential fluid would cause this. It's more noticeable inside the car than outside. It's not the air conditioner or the audio system. Really annoying. Any ideas? Belt?

[Crazy Bimmer]

Did they replace your air filter at the 1200 mile service? Maybe its not installed correctly?

[swamp2]

1. A very slight but noticeable whine from the DCT is normal but it should not have come only after your 1200 mi service

2. The 1200 mi service is not a "DCT service", it is an engine fluid and other fluids replacement.

3. I expect there is nearly a zero chance that they mistakenly changed your DCT fluid but it did happen to quite a few cars and most got the wrong fluid and had serious tranny problems that resulting in them being replaced. Double check with your dealer on this.

[Georgeair]

Originally Posted by swamp2

3. I expect there is nearly a zero chance that they mistakenly changed your DCT fluid but it did happen to quite a few cars and most got the wrong fluid and had serious tranny problems that resulting in them being replaced. Double check with your dealer on this.

As stupid as it would be for them to still be doing this, I would definitely get my hands on the actual service ticket from your visit. Preferably before starting this discussion.

You can search the forum for this topic, but as swamp pointed out it is terminal. Not eventually, but the moment the wrong fluid is put in and the car driven.

From what you described it sounds like the pitch and volume changes with speed, but cycles each gear. That doesn't sound like rearend to me and they shouldn't have been anywhere near anything else engine/trans related that should cause this. Could be coicidence and some other issue. We hope.

edit - just noticed you said also when revving in neutral. That's not likely to be the DCT either, is it?

[Polarstar]

Sorry, worded the thread incorrectly. Of course it's not the DCT service, but simply the 1200 mile service.

I did check the service ticket before posting, and the service appears to have been done correctly, with an oil change using the recommened oil, oil filter change, and differential oil change, again, using the correct fluid. No trans fluid change. Yes I read about the problems in changing the DCT fluid, so checked that right away. No air filter change as somebody suggested.

I did search the forums here and elsewhere extensively, and saw some similar cases, but nothing after the 1200 mile service; some suggested a belt, somebody spilled coolant on a belt and that gave a high pitched whine, somebody said alternator.

I agree that it doesn't seem like the transmission as the whine occurs while revving in neutral, again starting at about 1500 rpms.

It's going back tomorrow as for some reason the seat memory buttons no longer work, so I'll have them try to figure out this annoying whine. Driving me crazy!

[2fastcars]

Polarstar did you resolve the noise issue? I know the thread is about a year old, my 2009 has the same whine issue.

[Small Yellow]

Im sure its the airfilter or that box. I had some trash in that airbox that came from underneath the front intake where the bumper is and it made a weird whining rattling sound. Opened it up, removed the filter, and found trash there. That solved it.