Rare engine knocking sound when going over speed bumps

[x1canuck]

2014 28i xDrive here (close to hitting 100k-kms on mine) and I notice a weird sort of a knocking sound from the engine when driving over long bumps or perhaps train tracks. The knock happens very rarely, perhaps once in 1k-kms of driving and only when going over long bumps (a meter wide) and also train tracks. Sometimes when I hear the knock, I catch the CEL go on momentarily for 1/10th of a second - and it doesn't stick though, so there is nothing on the ODB2 scan. This has been happening for over 40k-kms and seems to be benign with no effect on driving or performance (the car drives great). I'm not so sure about longevity though and don't want this to came back and bite me later.

Anyone know if this might be related to the timing chain or such? given that people on this forum do speak about a preventive upgrade to the 2015 N20 chain guide/components.

I don't hear any whining from the engine bay either, just the standard clatter from the N20 which I've always heard. I'll ask the shop to specifically look at the timing chain the next time, but thought I should post here. FWIW, I've also moved away from runflats to regular tires which should help with less shock being transmitted to the engine bay, but I still notice the knock once in a while.

Cheers!

[Westies]

If it were the engine, it would knock more than a single time. This sounds like front suspension to me. The light flashing is the DSC/TC, which is very sensitive in these cars and will flash if you take speed bumps/train tracks/potholes quickly or at a weird angle. This is why you are not seeing a code from the scan.

[x1canuck]

Thanks a lot Westies! That makes sense. I'll keep an eye on the light to see if it is DSC/TC indeed.

[sudermatt]

I would check the engine mounts. My a e84 had engine mount problems at about 85000 miles