Check Subaru turbo inlet filter
This applies to all Subaru engines equipped with a turbocharger. Whenever a turbocharger is being replaced due to a failure, the cause may be a clogged oil supply mesh filter. The mesh filter is located inside the banjo bolt that secures the turbocharger oil supply pipe to the rear of the right side cylinder head. If the mesh filter screen is obstructed, it must be cleaned or replaced.
NOTE: The mesh filter screen is only available with a replacement banjo bolt P/N 14445AA090. The banjo bolt is to be torqued to 21.4 ft.-lbs. (29 Nm).
Make sure that the mesh filter screen is installed in the proper direction. Incorrect orientation will prevent oil supply to the turbocharger.
Do not confuse the turbocharger oil supply mesh filter screen with the Active Valve Control System (AVCS) union screw mesh filter screen.
In addition, if the turbocharger is replaced, it is required to remove the oil pan to inspect for sludge, metal and other debris. Oil supply/return lines, oil passages, etc., should also be checked if questionable. Don’t rule out a restricted oil filter.