As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FOLLOW-UP TO REPORT OF LOW LEFT DUCT PRESS AT IDLE. GROUNDED-YES. ACCOMPLISHED NR 1 ENGINE BLEED AIR SYS HEALTH CHECK, PER T/C NG-36WC-00002-1. NO FAULTS FOUND FROM T/C. DURING LEAK CHECK OF PNEUMATIC LINES FOUND PRSOV OPENING WITHOUT HAVING TO WRENCH OPEN FOR LEAK CHECK. ALSO FOUND PRSOV LEAKING FROM HOLE ON TOP BETWEEN BUTTERFLY VALVE. REMOVED & REPLACED NR 1 PRSOV, REF B737-900 AMM 36-11-04. LEAK & OPERATIONS CHECK GOOD. BLEED AIR CROSSOVER OPERATIONAL TEST CHECKS GOOD.