As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ENG 1 FAULT MSG 75-10591 FOUND. THE TBV POSITION SIGNAL IS OUT OF RANGE. LONG TIME FAULT. GROUNDED - YES. DEFERRED ON PLT FOR 450 FLT HRS PER T/C 78273000. REMOVED AND REPLACED #1 ENGINE TRANSIENT BLEED VALVE REF B737-800 AMM 75-23-01.