[Rob_G77]

I had this same issue with my X6 and now with my M850i. After driving the car a bit, I will park on a flat surface and turn the car off. About 2 seconds after turning the car off, I can feel and hear a dull sounding 'thump' which seems to come from the back end.

Any ideas about this? Does anyone else experience this? Mine is a 2022 M850i with 7500kms.

Rob

[bloozemanAZ]

Originally Posted by Rob_G77

I had this same issue with my X6 and now with my M850i. After driving the car a bit, I will park on a flat surface and turn the car off. About 2 seconds after turning the car off, I can feel and hear a dull sounding 'thump' which seems to come from the back end.

Any ideas about this? Does anyone else experience this? Mine is a 2022 M850i with 7500kms.

Rob

All I can add (as no clue as to what could be causing this) is I do not have the same effect on my 2020 M850i or the wife's 2017 X5. Given it sounds like a consistent repeatable event I'd have your dealer check it out. Rare gremlins are hard to track down vs the consistent ones.

[Tenac]

Curious are you putting into park before shutting it down?? I notice sometimes the wife gets a bit ahead of her self and hits the off button before hitting the P button and her X3 will thump bc the Park is engaging at the same time the engine shuts off.

[Rob_G77]

Originally Posted by Tenac

Curious are you putting into park before shutting it down?? I notice sometimes the wife gets a bit ahead of her self and hits the off button before hitting the P button and her X3 will thump bc the Park is engaging at the same time the engine shuts off.

I always put it in park before turning off the engine.

I'll take it in next week to see what's up. The thump seems to come from the rear of the vehicle.

Rob

[bloozemanAZ]

Originally Posted by Tenac

Curious are you putting into park before shutting it down?? I notice sometimes the wife gets a bit ahead of her self and hits the off button before hitting the P button and her X3 will thump bc the Park is engaging at the same time the engine shuts off.

I've shamefully am guilty of doing this with the M850i a couple of times when in a rush aka late for a meeting, etc. No thump but perhaps because I have auto hold activated so when going into park it puts the parking brake on. Perhaps without that is where the thump comes into play.

[MacOSR]

Originally Posted by Rob_G77

I always put it in park before turning off the engine.

I'll take it in next week to see what's up. The thump seems to come from the rear of the vehicle.

Rob

I’ll be curious to hear what they say because my M5 does the same thing but most of the time I think it is because I don’t put it in P first.

[wesleyan92]

This has been happening in my 2021 M5 comp since day 1. Never happened in my 2019 M5.

After I shut down, it is thud that comes from the rear end. At first I was worried something was going to break but I am at 23K miles now with no issues. Dealers have no clue.

On the M5 forum, someone mentioned that it could be coming from the exhaust system but I have no definitive clue.

I don't worry about it anymore.

[Tenac]

Wonder if anyone has captured the sound via go pro or something like that.??

[yugrac]

Silly as this may sound, any chance this is amplifier shutdown thud being heard and felt from the subwoofers?

[bloozemanAZ]

Originally Posted by yugrac

Silly as this may sound, any chance this is amplifier shutdown thud being heard and felt from the subwoofers?

Potentially but then the sound would appear to be from under the seats vs the rear.

[yugrac]

Originally Posted by bloozemanAZ

Potentially but then the sound would appear to be from under the seats vs the rear.

But I thought subwoofer frequencies were omni-directional, making determination of their point of origin difficult....

As your the resident expert on such matters, please school me

[bloozemanAZ]

Originally Posted by yugrac

But I thought subwoofer frequencies were omni-directional, making determination of their point of origin difficult....

As your the resident expert on such matters, please school me

They are but if just the subs taking a thump without any other noise in the cabin it would primarily be heard more directional than omni-directional. Plus the OP describes it as coming from the rear of the car which I took (and of course could be wrong) as in outside of the cabin, e.g., rear drive train.

[Rob_G77]

It's definitely not the subs.

I noticed a correlation between keeping my foot on the brake, pushing P and then turning the engine off seems to cause this. Which leads me to believe there is tension in the drive train from holding the brake and then that lets go when the engine is turned off?

Rob