As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
#1 (LEFT) MAIN FUEL TANK QUANTITY RAPIDLY DECREASED TO T-15 AFTER TAKEOFF. USING CENTER TANK FUEL. FUEL FLOWS AND FUEL USED NORMAL. GROUNDED - YES. PERFORMED BITE CHECK PER B737-900 FIM 28-41 TASK 801, NO FAULTS INDICATED CURRENTLY OR IN FLIGHT. RAN GROUND CHECK - NO FAULTS. AFTER REFUELING SAW INBAL INDICATION WENT AWAY AND FUEL LEVELS NORMAL. PERFORMED COMPARISON CHECK WITH FUEL STICKS, FOUND FUEL LEVEL CONFIRMS GAUGE READINGS.