As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APPROX 1 - 2 MINUTES AFTER ENGINE START, CREW NOTED SMOKE IN THE CABIN. ENGINES AND APU WERE SHUTDOWN AND A/C EVACUATED. SMOKE WAS TRACED TO THE BLEED AIR OF THE RT ENGINE. MX FOUND A DEFECTIVE CARBON SEAL PRESSURE REGULATING VALVE. THE VALVE WAS REPLACED AND THE AIRCRAFT RETURNED TO SERVICE.