As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED SMOKE SMELL IN AFT CABIN. MX FOUND THAT THE SMELL CAME FROM WHEN THE CREW SWITCHED BLEEDS TO THE APU RIGHT AFTER APU START. CHECKED THE APU FOR LEAKS AND FOUND NO ISSUES. RAN THE PACKS AND NO SMELLS RETURNED. OPS CHECKED GOOD. NO FURTHER DEFECTS WERE NOTED.