I keep losing air suspension lift option on acceleration
 

Strange fault. If I accelerate the light function is disabled and comes back on under heavier than normal braking

Any ides what could be causing this? I was wondering about the level sensors or maybe the pressure sensor on the pump wiring?

It's fine if I drive sedately and the functions do work when they haven't been disabled

2003 A8 D3 3.7l petrol quattro

To begin with, I'm going to assume that the word 'light' should be 'lift', and you're referring to the Lift mode on the MMI screen, and not the yellow and green warning 'lights' in the instrument cluster. Can you also clarify 'sedately' in terms of speed?

With that in mind, I wonder if you're just experiencing exactly what the air suspension is designed to do. The following snippet mentions the limitations of the Lift function, so if 'sedately' is under 63mph, then this would appear to be what's happening.

Further detailed information about the air suspension can be found in the following PDF from the 'D3 Tech dump' section:

56-SSP 292 adaptive air suspension in the Audi A8.pdf

yes, I did mean lift.

I cant really describe the rate of acceleration. .If I accelerate quite quickly (not maximum warp!) then the lift option on the MMI becomes disabled. It tends to stay like this until I brake quite sharply (gentle braking doesn't seem to enable it) I think it might cruise for hours in the disabled state until fairly sharp braking occurs again?

I will check out the link you provided though - thank you

Would that be like doing a 0-60 run type acceleration? You mentioned the level sensors, and that might be the issue, although I would have thought that if there was issues with one of them regarding readings, it might flag up one of the suspension lights.

I can't think how mechanically a level sensor can get 'stuck', if it still attached properly, so maybe a dodgy connection due to water ingress, or water ingress into the actual electronics.

Do you have VCDS or other diagnostics tool that you could use? I suspect there's bound to be measuring blocks in module 34 (Level Control) that you could check for the four sensors, to see if they are all within the same tolerance. In theory, you should also be able to check these values whilst cycling through the various suspension settings. Then again, they might all show up as fine whilst stationary. VCDS does allow you to log data, so maybe you could start logging the four sensors, go for a normal drive, and try to replicate the issue, and then check the results.