As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BLEED AIR DUCT PRESSURE SPLIT AT CRUISE FL380. RIGHT PRESSURE READS 41, LEFT PRESSURE READS 18. PERFORMED PNEUMATIC SYS TROUBLESHOOTING IAW AMM 36-11-00-700-804. FOUND NR 1 ENGINE PRSOV VALVE DEFECTIVE. R & R PRSOV IAW AMM 36-11-04-400-801. ACCOMPLISHED ENGINE BLEED AIR CROSS-OVER OPS TEST IAW AMM 36-11-00-710-801. OPS CHECKED GOOD. ACFT OK FOR SERVICE.