As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING DESCENT LEFT BLEED LIGHT ILLUMINATED. RESET PER QRM. LIGHT CAME BACK ON AFTER A FEW MINIUTES. GROUNDED - YES. FOLLOWED MX MSG 36-00160. PERFORMED INITIAL EVALUATION B. THE FAULT ISOLATION PROCEDURE. C MAINTENANCE MESSAGES FOUND IN 36 PNEUMATICS. STEP (2) REPLACE HIGH PRESSURE SHUTOFF VALE (ENGINE 1). REMOVED AND REPLACED #1 ENG HPSOV REF B737-9 AMM 36-11-07. NO LEAKS NOTED AND ALL TESTS PASS AT THIS TIME.