As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SMOKE TOILET INDICATION DURING DESCENT. INDICATION CLEARED AFTER ABOUT TWO MINUTES. RAN QRH. FLIGHT 3861. FOUND COMPRESSOR ROTOR SHAFT SEAL TO BE LEAKING OIL INTO THE INLET AND INTO THE BLEED AIR PATH. REMOVED AND REPLACED THE APU ASSEMBLY, OPS AND LEAK CHECKS GOOD. OPERATED PACKS OF APU BLEEDS, NO ABNORMAL SMELLS, OR SMOKE INDICATIONS NOTED IAW AMM.