Wednesday was the first cool day since I bought the car. After starting, I got a suspension fault message. After the car warmed up, and was shut off for a few minutes before restarting, light was gone.

Yesterday was colder still, but no fault message. Car has 142,000 miles on it.

This morning the front was sitting on the bump stops with "Car Too Low" and "Suspension Fault". As on Wednesday, after the engine compartment warmed up, and car was shut off and restarted, problem was gone.

My X308 was really sensitive to voltage changes. My first thought is this is a resistance problem. Since it seemed to be just the fronts affected, I cleaned the electrical connector on top of each from shock after disconnecting the battery. I followed this with a hard reset before reconnecting the negative battery terminal.

My X308 had to have all ground stud and connecting wires cleaned. Are the X350 cars prone to the same problem?

Any other thoughts?

 

This behaviour during cold looks like something starting to become weak in your suspension system, either in the compressor (the bagpipingandy kit is a must to cure that) or seals in one or more shocks.
You may look for leaks using soapy water on top of the shocks.