As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RECEIVED MSG, L OIL FILTER STATUS AFT ENG START. NO CONTAMINATION IN C-D'S OR FILTERS. REPLACED MAIN OIL FILTER. RAN ENGINE, NO LEAKS DETECTED. CHIP DETECTORS CLEAN. NEED TO REPLACE DIFF PRESS SWITCH AT FIRST OPPORTUNITY. REPLACED DIFF PRESS SWITCH. NO DEFECTS NOTED.