As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT DUCT PRESSURE INDICATOR FLUCTUATED DURING CLIMBOUT AT 3 SECOND INTERVALS. INITIALLY 35 PSI TO 55 PSI, ABOVE 10 000' 35 PSI TO 50 PSI. FLUCTUATION QUIT APPROACHING FL190. BOTH INDICATORS FLUCTUATED TOGETHER THEN SETTLED OUT. PERFORMED NR 1 ENGINE BLEED AIR REGULATOR AND PRSOV HEALTH CHECK. PRSOV FAILS HEALTH CHECK. REPLACED PRSOV & BLEED AIR REGULATOR. OP CHECKED BLEED AIR CONTROL SYSTEM. OP CHECKS OK NO FLUCTUATIONS OR ABNORMAL INDICATIONS.