BlackOptic

My 2017 TTS was doing the same thing. Totally random. I've seen other forums discuss... I've now heard (random) explanations including:-

a) side bolsters deflate when shutting the car down, and pump up 5 mins into driving... (I'll have to check the MMI)
b) lumbar support 'stiffens up' when driving aggressively?

EDIT... from the TT User's manual...

TJEli

Our S5 is doing this now too at random times.

-Eli

Bill17601

it happens in my car. Just goes once or twice then stops, thought I’d left the massage function on.

Denn1s

Mine keep rubbing my inner thighs, lead me to a happy ending, I love my S5!

Bill17601

need pictures of how your sitting in the seat. Tried 13 different positions and can’t replicate your experience.

N8!

I'm not sure I am understanding Denn1s' anatomy - but, hey... what do I know..

rocko76

Wow... I was never expecting so many with the same behavior. I'm not sure if I'm comforted or more concerned. I struggling to think that this is "supposed" to happen (why wouldn't the lumbar support stay at the drivers setting like all of the other seat adjustments - and it's not consistent and it isn't a minor adjustment as I now see some other threads say is intended to combat back fatigue), but that's a LOT of people with gremlins if it is unintended.

freesole

Yup. My wife is always going, "What the hell?" It just turns on randomly and stops abruptly.

-=Hot|Ice=-

There has to be a reason it happens. Do the bolsters inflate when cornering hard? Maybe if the car senses an impact it tries to prime the occupants?

N8!

Is this issues only seen in S5's w/massage capability?

My A5 S-Line seats retain their inflation and so far do not exhibit any of the signs discussed in this thread (I have 5100 miles and have owned the car since late June).