As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PRESSURIZATION AUTO FAIL LIGHT ILLUMINATED DURING CRUISE FL 390. SYS REVERTED TO ALTN MODE AND OPERATED NORMALLY. ACFT GROUNDED. PERFORMED A DIGITAL CABIN PRESSURE CONTROLLER BITE PROCEDURE IAW FIM TASK 21-31, TASK 801. NO PRESENT FAULT. GROUND TEST SYSTEM OK.