As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE CHECKING C/B'S PRIOR TO TOW FOUND C/B P 6-4 B7 (AIR CONDITIONING BLEED AIR VALVE RIGHT) POPPED. GROUNDED - YES. TROUBLE SHOT PER B737-800 WDM 36-11-11 AND FOUND OPEN SIDE OF ENG 2 BLEED AIR REGULATOR TO BE SHORTING. REMOVED & REPLACED BLEED AIR REGULATOR OP'S CK & LEAK CHECK IS GOOD. REF B737-800 AMM 36-11-03-400-801 / 36-11-03-000-801.