As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PDX - MAINTENANCE FOUND THAT WHEN THE ADVISORY LIGHT TEST IS PERFORMED, THE FIRE WARNING BELL IS TRIGGERED. AFTER INSPECTING THE SYSTEM, CLEANED THE RIGHT AND LEFT NACELLE ENGINE AND MAIN LANDING GEAR PRIMARY ZONE ADVANCE PNEUMATIC DETECTOR CANNON PLUGS. OPERATIONAL CHECKS WERE GOOD AND THE AIRCRAFT WAS RETURNED TO SERVICE. NO PARTS WERE REPLACED.