Slight clonk soon after turning on

Anyone else have this? You turn on the car with the start/stop, and maybe 10 seconds later, whether you've pulled away or are still stationary, a "clonk" goes through the car, like some big relay has activated underneath. I haven't mentioned that one to the dealer yet.

Definitely NOT in my case.

Not had that, no problems to report.

I experienced this on two occasions today. First time I was sitting in the car park at Waitrose heard a clonk and thought someone had hit me but there were no cars around. Second time happened in my driveway again the car was stationery but car was in ready mode. I think maybe we should report this.

Mine has the same - but I've only noticed it after pulling off, like it was locking the doors. Perhaps disable the setting to auto lock the doors and see if you still hear the clonk?

Ah, nice idea, but definitely not the doors auto-locking. It seems to come from underneath the car...

It's not happening nearly so often now - maybe once since I posted this up. Strange.

AndyW said:

It's not happening nearly so often now - maybe once since I posted this up. Strange.

Click to expand...

Good to hear Andy!

I've never had a klunk but have had the rear door "problem" once!
It happened when waiting on my fellow passenger to pull something from the back seat just before leaving and she closed the rear door too carelessly. The door locks went on and off when accelerating and rounding corners. When we stopped to check the door, she noticed that her scarf partially extruded under the front door. She stepped out and firmly closed (not with a slam) the doors again and all was well!

An idea on the klunk: maybe some loose item in the front storage area?

I recognize the "klunk" sound; mine does too. I only did not figure out when, and where it comes frome.

As for the back doors detecting to be opened; experienced this too a few times. I only have the car for a week now, so i will take the time to observe this longer before i report this to the dealer.

My klonking also seems to have stopped. Only happened for the first few days....strange!

I also have the klonk thing, its comes from the front, you can feel it when your foot is leaning against the plastic.
I wanted to but haven't managed to record it yet !
I heard it could be somehow related to the heatpump, did you guys pick that option ?

I've had this noise for more than a month now.

Nope, definitely not the doors locking, or anything to do with the other problem of the rear doors not being engaged properly. It comes from underneath the car, towards the front. You can feel it through your feet, through the floor of the car.

Mine doesn't do it any more though, strangely.

I did speak to a chap once who'd run over his own cat on his drive in his Lexus hybrid

No, this sounds like a big relay or solenoid kicking in, I'd say.

I had the same clink which felt as if it came from under the front left side of the car.

I had my foot on the break and was at a standstill in my garage with the parking break on.

After about 20 seconds of having my foot on the break, I heard and felt the klunk.

I thought it was something to do with the parking break.

Have not brought it up to the dealer yet but will send them an email tomorrow.

I am pretty sure that is the ABS system doing its self-check. If you insist one can verify it by pulling the fuse, driving a little (ABS is needed in extreme situations and many cars do not have it, so it is not a problem on a quiet local road, breaks are still 100%), then put the fuse back. You will get some error codes but the clunk should not be there... There is no fix but at least you know not to worry.

Ole from the Facebook group, an engineer, agrees that it's a brake check. His explanation (slightly edited for clarity):

"...the i3 has an automatic brake washing system that maintains brake operations at all times - it will do a massive pump on every wheel (rotating with one wheel at a time) on the first standstill after every start-up (yes, that's the "clunk" sound you're all hearing sometimes). It will also wash the brakes by slightly applying some brake to disc pressure during free-roll in downhills, when the rain sensor detects rain (to wash away rust). The latter is common on all new BMW's "

And:
"...it is a full ABS pulse (like those you get under normal ABS braking), but it only happens if the car gets to standstill just a few seconds after take-off, and on only one wheel at a time ("round robin" scheme)."

So there you go! Thanks Ole

Cunning!