As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT DUCT PRESSURE MODULATED FROM 0 PSI TO NORMAL @ 12,000 FT. LEFT DUCT INDICATED 0 PSI @ FL 230, 5 MIN LATER RECORDS TO 14 PSI (RIGHT INDICATED 34 PSI). EICAS MESSAGE LEFT ENGINE BLEED OFF WAS ALSO INTERMITTENT (<P>FAN AIR VALVE WAS REPLACED DURING C-CHECK FOR RELIABILITY. NEW FAV FAILED DURING TEST FLIGHT, BFS. ORIGINAL FAV INSTALLED BACK ON #1 ENGINE PER AMM 36-11-16/401. ASM CHECK CARRIED OUT WITH NO DEFECTS NOTED.</P>)