I've not actually owned or diagnosed one of these, so take my advice with a grain of salt- but I would expect one could disconnect and pressure test each shock individually by unscrewing the line, screwing on a regular schrader valve, carefully adding a little pressure with an air pump, and seeing how long it takes to drop.

For a 13 year old car with an incredibly complex suspension, I'd probably want 4 new shocks anyways personally- but certainly there could also be a leak not in the shocks.

 

Yes this is my thought aswell, it needs to be done soon anyway, from what is see its still on original parts. The car has made 18.000km and rides very smooth still.. i think i will replace the 4 air bags... Does someone know a reliable cheap set? I know those 2 dont go hand in hand but im not spending half the cars worth for new air shocks..

 

Get some soapy water and start spraying all connections/fittings. Airbag, line, valve block.

 

This is done! Ive sprayed everything i can reach, can these shocks have internal leakage?

 

These airbags are serviceable. Usually this one is to blame: 7P6412327. Number 3 on the diagram.

 

Yes, i am looking into service parts aswell, but found pretty cheap bags from aerosus. Would you recommend me servicing them or replace the bags aswell? I plan on keeping this car for a couple of years..

 

found pretty cheap bags from aerosus.

Cheaping out on critical suspension parts. Nice.

 

I, personally, plan to service them during spring, when its warmer. Parts are pretty cheap and worth a shot.

 

Do you know the sizes of both o-rings?

 

Went out and sprayed over the top again but could not find any leaks, i am now also hearing this low hissing noise coming from the front shocks, i cant really locate it but middle/lower part of the shock. I'll order new bags while i still have to do the same work...

 

On diagram:
3: 7P6412327
6: 7P0412269A
16: N90367701
7: 7P0616045 (Additionally, where o-ring 7 goes, there can be added another 2: Elring 889.512 (56*60*2))
11: 7L0616817