As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
L/H DUCT PRESSURE SHOWING 18 PSI WITH ALL BLEEDS CLOSED, APU OFF AND ISOLATION VALVE CLOSED, BLEED VALVE SWITCH WILL NOT SHUT OFF AIR ON #1 ENG. GROUNDED - YES. REMOVED #1 ENG PRSOV AND REPLACED WITH NEW PRSOV REF B737-800 AMM 36-11-04.RAN #1 ENG, TURNED APU AND #1 ENG BLEED OFF, 0 PSIG ON GUAGE SHOWN. OPS CHECK GOOD.