As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WITH #1 BLEED SELECTED OFF ENGINE STILL PROVIDES 16 PSI TO THE BLEED AIR DUCT AT IDLE AND AS HIGH AS 35 PSI WHEN USING BREAKWAY THRUST. BLEED AIR ONLY WENT TO ZERO WHEN THE #1 ENGINE WAS SHUTDOWN. GROUNDED - YES. REMOVED AND REPLACED BLEED AIR REG. PER B737-900 AMM 36-11-03.