As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RETURNED TO THE FIELD WHEN UNABLE TO PRESSURIZE PLANE. SUPPLEMENTAL DATA UPDATE ACCOMPLISHED LEAK CHECK. PRESSURIZED ACFT SEVERAL TIMES ON GROUND ACFT PRESSURIZED NORMAL. NO HARD FAULT WAS ISOLATED. ALL RESPECTIVE ATA SYSTEMS AND SUB-SYSTEMS WERE CHECKED. REPLACED CABIN PRESSURE CONTROLLER (CPC) AS PRECAUTIONARY.