As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT FUEL FILTER BYPASS LIGHT ILLUMINATED AT APPROX 1000' AGL AFTER T/O. ACFT GROUNDED. RETURNED TO DEPARTURE. ON ARRIVAL, FOUND NO FILTER BYPASS LIGHT ENGINE NR 1, PERFORMED EEC BITE TEST, GV OF SWITCH AND CONNECTOR FILTER BYPASS SHOWS NO CLOG. REPLACED NR 1 ENGINE FUEL FILTER. OPS AND LEAK CHECKED GOOD, IAW MM 73-11-02. REPLACED NR 1 ENGINE FUEL DIFF PRESSURE SWITCH IAW AMM 73-34-01, OPS CHECK GOOD.