CODE P0193 all that was left?

How is the code listed? You basically have Pending codes - these are ones that take 2 failures before they set a current code, the you have current codes, these are the ones that are active now. These become history codes if the system sees the fault stopped (or another code set that stopped the first codes test) then there are permanent codes, these set so that the folks who like to clear codes to shut off the light during a sale cannot say " Oh it's in great shape with no problems". Those will not clear until a set number of key or run cycles pass without the failure happening again.
Did find some other service info that shows this as the code definition -
Generic - P0193 MB Code ID - 3628 B4/15 (Fuel pressure sensor) Short circuit to positive or open circuit.
So basically the 5 volt circuit has an issue where it either grounds out or it drops out entirely. The problem is finding where it's failing, it could be internal to the ECM but that would be hard to trace without an O-scope to watch as you move things around.

Then hopefully it's a code that has to clear on it's own because those are the items the MB service info points at. I managed to get access to a MB dealer account for a bit and looked up a few issues, yours included. MB service info doesn't impress me much, it is very dependent on the OE scan tool system to do in depth work. Priced one just as fun, for the better system it was $34,000.00 !