As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BOS/CLT - FLT 1638 - DURING CRUISE, THE LEFT ENGINE OIL FILTER CLOG LIGHT ILLUMINATED. ENGINE THRUST WAS REDUCED, BUT THE LIGHT REMAINED ON. THE ENGINE WAS SHUT DOWN AND THE AIRCRAFT LANDED WITHOUT INCIDENT. THERE WAS 20 MINUTES SINGLE ENGINE TIME. MAINTENANCE REPLACED THE LEFT ENGINE OIL FILTER. (X)