As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PDX FLIGHT NR 2308: ON CLIMB-OUT, NR 1 FUEL TEMP WENT TO 74 DEG C AS PER CHECKLIST, TURNED ON NR 1 AUX PUMP. THE TEMP DROPPED TO 71 DEG C AND THEN LOWERED. AS PER CHECKLIST, THE PUMP WAS TURNED OFF. THE TEMP CLIMBED BACK UP. THE PUMP WAS THEN TURNED BACK ON AND THE TEMP DROPPED. MAINTENANCE REMOVED AND REPLACED THE NR 1 ENGINE FUEL HEATER IAW Q400 AMM 73-11-01-000-801 AND 73-11-01-400-801. OPS AND LEAK CHECKS GOOD. AIRCRAFT RETURNED TO SERVICE.