As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT FUEL QUANTITY INOP/ ERRATIC. INDICATED 4000 POUNDS LESS THAN CALCULATED. AIRCRAFT REMOVED FROM ETOPS SERVICE. *S/D* LEFT MAIN TANK UNIT NR 6 (TS309) WAS FAULTED BY THE FQIS PROCESSOR. THE TANK UNIT WAS REPLACED AND THE SYSTEM TESTED WITH NO FAULTS. TO DATE SYSTEM FUNCTION HAS BEEN NORMAL SINCE REPLACEMENT OF THE DISCREPANT TANK UNIT.