As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LT ENG BLEED VALVE OFF LIGHT WITH ASSOCIATED LEFT ENGINE BLEED AND LEFT PACK OFF LIGHT. AIRCRAFT BACK TO GATE. AIRCRAFT GROUNDED. VERIFIED PRSOV WON'T OPEN, REMOVED AND REPLACED LT ENG PRSOV. OPERATIONS CHECKED GOOD, IAW B767 MM 36-11-18. REMAIN ETOPS 180.