Subwoofer turning off (2021 M235i)

Jerry_inPNW · 06-19-2025, 07:28 AM

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The subwoofer occasionally cuts out for a second or so. Not very often, perhaps once/twice an hour. Up until now, not often/long enough for me to investigate. The other day though, when I left work, the moment I turned on my car, (cold) I had no subwoofer; it was like that for the entirety of my short trip home (about 10 minutes, 68 degrees). The next morning, the subwoofer was fine again.

I'm not sure what could be causing the sub to stop nor where to look. I don't know where any of the stereo components even are.

I've had this car for about 16 months and this has been the only issue. Last owner ticked all the options (except seats) so as far as I know it has the high end H/K system for the F44, whatever that is. I assume it's used in other BMW models too. It sure sounds good.

DomMuc · 06-19-2025, 10:37 AM

there is a servicebulletin that advices the tech in this case to replace the ram-module... if you do not have warranty anymore you´ll be paying the bill ( ~1,5k)

RMNB · 06-19-2025, 11:09 AM

BMW service bulletins.pdfOP - have them check to see if it's a simple wire connection. I feel I have a similar problem but the sound i hear in the rear sounds like a "knock" coming out of a speaker.

See attached what I just found.

Jerry_inPNW · 06-21-2025, 07:24 AM

Thanks for the heads up! I think I'm just past the warranty now.

No knocking sounds for me when it happens, just a complete loss of bass/low end spectrum.

If it is the memory, is this something typically only a dealer can replace or are crafty people doing DIY ram fixes? I suspect it's funky proprietary stuff.

06-19-2025, 07:28 AM	#1
Jerry_inPNW New Member 3 Rep 6 Posts Drives: 2021 M235i (F44) Join Date: Mar 2024 Location: Washington iTrader: (0)	Subwoofer turning off (2021 M235i) Featured on BIMMERPOST.com The subwoofer occasionally cuts out for a second or so. Not very often, perhaps once/twice an hour. Up until now, not often/long enough for me to investigate. The other day though, when I left work, the moment I turned on my car, (cold) I had no subwoofer; it was like that for the entirety of my short trip home (about 10 minutes, 68 degrees). The next morning, the subwoofer was fine again. I'm not sure what could be causing the sub to stop nor where to look. I don't know where any of the stereo components even are. I've had this car for about 16 months and this has been the only issue. Last owner ticked all the options (except seats) so as far as I know it has the high end H/K system for the F44, whatever that is. I assume it's used in other BMW models too. It sure sounds good.
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06-19-2025, 10:37 AM	#2
DomMuc Captain 768 Rep 622 Posts Drives: G87 M2 Join Date: Nov 2012 Location: Munich iTrader: (0)	there is a servicebulletin that advices the tech in this case to replace the ram-module... if you do not have warranty anymore you´ll be paying the bill ( ~1,5k)
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06-19-2025, 11:09 AM	#3
RMNB Lieutenant Colonel 380 Rep 1,675 Posts Drives: 2021 M440xi BSM Join Date: Jul 2013 Location: Maryland iTrader: (0)	BMW service bulletins.pdfOP - have them check to see if it's a simple wire connection. I feel I have a similar problem but the sound i hear in the rear sounds like a "knock" coming out of a speaker. See attached what I just found. Last edited by RMNB; 06-19-2025 at 11:21 AM..
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06-21-2025, 07:24 AM	#4
Jerry_inPNW New Member 3 Rep 6 Posts Drives: 2021 M235i (F44) Join Date: Mar 2024 Location: Washington iTrader: (0)	Thanks for the heads up! I think I'm just past the warranty now. No knocking sounds for me when it happens, just a complete loss of bass/low end spectrum. If it is the memory, is this something typically only a dealer can replace or are crafty people doing DIY ram fixes? I suspect it's funky proprietary stuff.
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