As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TAXI OUT, LT BLEED ISLN VALVE NOT IN THE COMMANDED POSITION AFTER ENGINE START. A/C RETURNED TO BLOCKS. (BTB). REMOVED & REPLACED LEFT BLEED ISLN VALVE IAW AMM 36-11-04, OPS CHECK OK IAW AMM 36-11-04 AIRCRAFT REMAINS NO ETOPS. AIRCRAFT RETURNED TO SERVICE.