I waited a couple of days to see if anyone else offered anything.
I tried searching for that code but the closest I could find was DSB 02 which is "Key not present or transponder broken"
Personally I wouldn't worry as long as the red triangle has disappeared.
I think the original error may have been caused by a weak or flat battery or bad connection.
Always scrape the battery terminals to expose shiny lead then apply some grease to exclude Oxygen, Vaseline is my grease of choice.
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Has your friend done the "Startus Interuptus" fix on his bike otherwise its only a matter of time until it refuses to start and give the dreaded click even with a fully charged battery.
The Starter solenoid would like to have over 40 Amps to pull the gear into place and close the main contacts, unfortunately the factory wires choke this back to about 25 Amps on a good day and route it through the ignition switch to boot.
http://www.thisoldtractor.com/guzzi007/schematics/2007_Norge.gif The yellow feed to the Start Relay (3) is weak and the wire from the relay to solenoid is undersized.
The usual fix is to snip the yellow wire just before the relay and tie it to a new 20 Amp in-line fuse direct from the battery, most owners don't bother but the wire from relay to solenoid should be increased a size as well, 16 AWG or 1.5 mm2