As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TAKEOFF ROLL, BLD 1 VLV FAIL EICAS MSG APPEARED. THE CREW ABORTED THE TAKEOFF & RETURNED TO THE GATE. UPON TROUBLESHOOTING IT WAS FOUND NR 1 ENG HIGH STAGE PRESS SWITCH FAILED, THE SWITCH FELL APART. REPLACED THE HIGH STAGE PRESS SWITCH WITH NEW. OPERATIONS CHECKED GOOD. THE ACFT WAS RETURNED TO SERVICE.