As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT CREW REPORTED THAT THE NR 1 ENG OIL BYPASS LIGHT ILLUMINATED DURING FLIGHT WITH NO SECONDARY INDICATIONS. TROUBLESHOOTING CHECKED THE ENG OIL FILTER FOR BLOCKAGE, NO BLOCKAGE FOUND. FURTHER TROUBLESHOOTING REVEALED THAT THE OIL BYPASS PRESS SWITCH WAS DEFECTIVE. THE DEFECTIVE SWITCH WAS REMOVED PN 45AS42011-001 SN 2826 & A NEW CONDITION SWITCH WAS INSTALLED. OPERATIONS & LEAK CHECKED SATISFACTORY.