As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
#1 FUEL FILTER BYPASS LIGHT IS ON WHEN ENGINE IS RUNNING. GROUNDED - YES. REMOVED AND REPLACED FUEL FILTER DIFFERENTIAL PRESSURE SWITCH REF B737-800 AMM 73-34-01. REMOVED AND REPLACED FUEL FILTER, REF AMM 73-11-02. ACCOMPLISHED TEST 3A DIFF PRESS SWITCH AND FILTER, NO LEAKS NOTED.