As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE PERFORMING ASA T/C 78273000 FOUND #1 ENG FAULT 75-10591 THE TBV POSITION SIGNAL IS OUT OF RANGE. LONG TIME FAULT. GROUNDED - YES. TBV RECEPTACLE DP907 OUT-OF LIMITS REF. B737-800 FIM 75-23/802 STEP (4). REMOVED AND REPLACED TRANSIENT BLEED VALVE PER B737-800 AMM 75-23-01.