As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: NOTICED MUSTY ODOR AT TOP OF DESCENT WHEN POWER WAS REDUCED TO IDLE. CABIN CREW DID NOT NOTICE ANYTHING. MAINTENANCE FOUND SOURCE OF COCKPIT ODOR TO BE CLOGGED/DIRTY AVEC FILTER. RELACEMENT OF FILTER SOLVED COCKPIT ODOR.