As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: AT LEVEL OFF THE LEFT WING TANK WAS 600 LBS LESS THAN THE RIGHT. TOTAL FUEL QUANTITY WAS EXACTLY AS EXPECTED.: FFC SERVICES REMOVED, REPLACED, AND CAP CHECKED LEFT WING NUMBER 4 PROBE. PER B737 AMM 28-41-21. CAP CHECK GOOD.**(CLOSED).