As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CLIMBING THROUGH FL 385 MASTER CAUTION LIGHTS ILLUMINATED AND BLEED TRIP OFF LIGHT ILLUMINATED RT DUCT PRESSURE WAS 10 PSI. RAN QRH 2.4 AFTER THIRD RESET, PER QRH CAUTION LIGHTS EXTINGUISHED. RT DUCT PRESS FLUCTUATED THEN RESTORED TO 30 PSI. GROUNDED-YES. PERFORMED FULL NR 2 ENGINE BLEED AIR SYSTEM HEALTH CHECK FOUND PRECOOLER CONTROL VALVE OUT OF CHECK LIMITS, REF T/C NG-36WC-00002-2. REMOVED AND REPLACED PRECOOLER CONTROL VALVE, REF B737-800 AMM 35-12-02. PERFORMED ENGINE RUN AT 65% N1 SETTING. NO DEFECTS NOTED.