As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SHIP 5815 PACKS ARE EMITTING STRONG SMELL SIMILART TO EXHAUST. ISOLATED R RECERS FAN AND SMELL DEMINISHED. ON FINAL DECENT SMELL RETURNED. ISOLATED L PACK & SMELL DEMINISHED AGAIN. CORRECTIVE ACTION: T/S R/R LH + RH RECIRC FILTERS PER B757 AMM 21-25. REMOVED AND REPLACED #2 ENGINE.