As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SEA - VERY PUNGENT STENCH FROM BLEED SYSTEM WHEN POWER IS BACK, ON DESCENT, BLEED AIR ON. GROUND RAN ENGINES, ISOLATING BLEED AIR BY OPERATING ONE BLEED AT A TIME. NO SIGN OF ENGINE INGESTION. CLEANED AIR CYCLE MACHINE INLET SCREEN. AIRCRAFT RETURNED TO SERVICE.