2010 X351 TDV6
I have had this problem for a while, at first it was very intermittent, after driving for a while would get a warning Suspension Fault, followed by a yellow warning triangle on that dash, this would disappear and after 5 or so minutes then i would get the same message and again after a short while the warning would go away, only to come back a little while later.

One day it came on as soon as i started the car and stayed on, I changed out the air compressor for a brand new Proevo+ unit and had no faults for a couple of weeks, then the fault stated again at first it was intermittent and then when permanent as described above.
I have changed the R10 compressor relay, but this hasn't helped.

I noticed after a drive the compressor was very hot, the car was parked up for 8 hours while i was at work and i checked the compressor again, without started the car and again the compressor was really hot, it was still working with the car switch off and locked. I have removed all the electrical connection from the compressor 2 days ago and the rear suspension has not sunk, so the system is leak free.

The error code i get is : C1A27-12 Compressor Circuit.

Thanks in advance

 

System can still have a leak. Compressor is filling the resevoir and air springs work from the resevoir thru valve block. If rear dont sunk, you only know that there are no leaks between shocks and valvebody.

 

When I swapped my air compressor one of the must do's was to swap in a new connector. Let me see if I can find it.