As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SEA- FLIGHT 2503, RECEIVED A LEFT BLEED CAUTION MESSAGE, RETURNED TO THE GATE. MAINTENANCE PLACED THE SYSTEM ON MEL 36-11-2 AND RETURNED THE AIRCRAFT TO SERVICE. IN PDX ON 8/30/07, MAINTENANCE REPLACED THE NR 1 ENGINE PRSOV. AIRCRAFT RETURNED TO SERVICE.