As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMBOUT RT PACK DUCT PRESSURE @ 8 PSI. GROUNDED - YES. AIR TURNBACK -- ACCOMPLISHED PNEUMATIC- TROUBLESHOOTING PER B737-800 AMM 36-11-00-700-804, FOUND BAD BAR AND PRSOV. REMOVED & REPLACED THE #2 ENG. BLEED AIR REGULATOR AND PRSOV, REF AMM 36-11-03 AND 36-11-04.