As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE FLIGHT, ENROUTE, THE AFT FUEL CELL LOW LIGHT ILLUMINATED. TRANSFERRED KNOWN QUANTITY OF FUEL INTO AFT FUEL CELL WITH NO RISE IN AFT TANK INDICATION. ACFT DIVERTED WITHOUT INCIDENT. R & R AFT FUEL CELL INDICATOR GAUGE AND CALIBRATED TO AFT TANK.