As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PDX FLIGHT NR 2359: ENG ADQT HEAT 1 CAUTION LIGHT. MAINTENANCE REMOVED AND REPLACED THE NR 1 ENGINE INTAKE ADAPTER HEATER IAW Q400 AMM 30-21-15-000-801 AND 30-21-15-400-801. OPS CHECK OF THE ENGINE AIR ANTI-ICING CHECKS GOOD. AIRCRAFT RETURNED TO SERVICE.