As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WITH LEFT ENGINE ANTI-ICE ON, COMPLETE LOSS OF LEFT AIR SYSTEM PRESSURE (I.E. PACK AND BLEED AIR EICAS IN CRUISE, L DUCT PRESS 18 PSI).(<P>AS PER FIM 36-10 FAULT TREE 837, REMOVED AND REPLACED PRV CONTROLLER ON LEFT ENGINE PER AMM 36-11-19. OPS CHECK LEFT ENGINE IDLE RUN OK.</P>)