As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: LEFT FUEL FILTER BYPASS ILLUMINATED. REMOVED AND REPLACED ENGINE NUMBER 1 FUEL FILTER DIFFERENTIAL PRESSURE SWITCH, PER AMM 73-34-01-400-801-F00 AND PERFORMED EEC TEST, PER AMM 73-21-00-700-804. OPERATIONAL AND LEAK CHECKED GOOD, NO FAULT AT THIS TIME.