strangely enough in the Tier2 mfca TC-2005 updated error code list code F-73 is listed as empty, no code designation defined.
codes F-72 and F-74 are designated as attachment 3B solenoid error and attachment solenoid leak error codes.
Now in 2009 they released another code list in MCFA document #000134-09C where it designates error code F-73 as an hour meter gap (hour meter time difference between VCM and meter panel).
The fix for this is to use the service tool and reset line #197 to zero for M/P hour-meter.
When you do this the meter panel reacquires the stored hour meter from the VCM.