As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
Lt eng hi stage displayed. Lt hi stage light illuminated. Per non-normal check list the left pneumatic switch was cycled on/off with oily fumes coming into the cabin. Note: The remainder of the flight was operated with left engine bleed and left A/C pack off. Fumes cleared. Left pneumatic pressure read 14 psi with left side switch off. Replaced fan air temp sensor. Leak and ops checked good IAW B767 MM 36-11-17-4.