As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON TAXI OUT, DURING LEFT ENGINE CROSS BLEED, START VALVE LIGHT REMAINED ILLUMINATED AND DUCT PRESSURE DROPPED TO ZERO. A/C RETURNED TO THE GATE (BTB) AND MTX GROUNDED A/C. MTX DEFERRED LEFT ENGINE START VALVE PER MEL 80-00-2-1 PLACARDS INSTALLED, MX PROCEDURE C/W. ACFT REMAINS NO ETOPS MBCB 07/30/2026. A/C RETURNED TO SERVICE.