It is the left front actuator. But I think maybe it is some electrical connection of the actuator
That used to happen with mine - then after a while it stayed on full time as the adjuster gave up the ghost.When the ignition is turned on, each adjuster rotates fully in one direction and then the other to check that the adjusters are working and the shock absorbers themselves are able to turn and respond. If any of the 4 units refuse to comply then the error message appears.
What is happening is that one of the shock absorbers or (more likely) the adjusters is sticking and as you say when it is warm it is enough to free it up. A dealer or a good independant can plug into the diagnostics (OBD on later cars SD2 on earlier) and determine which corner is the culprit, even if the error isn't showing at the time because it remembers. I had something similar and bought some time by removing the adjusters and spraying the mechanisms in WD-40.