All these things are on the CAN bus (yes, Oldtimers, MB's went digital in the late 90s). You can try to reset it by disconnecting the battery for about 2 minutes, but make sure you have your radio code 1st.
One of the 9-10 devices on the bus is acting up and triggering faults elsewhere. The PSE pump is a major one, and it sits behind the battery under jute padding underneath the rear seat. Check that it is not wet, because there's a circuit board in its base.

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Prost!