As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED AN OILY SMOKE SMELL IN COCKPIT AND CABIN AFTER NR 2 ENGINE STARTED ON PUSHBACK. CREW RETURNED TO GATE IN CLT. MAINTENANCE REMOVED AND REPLACED THE AIR CYCLE MACHINE IN ACCORDANCE WITH THE AIRCRAFT MAINTNENANCE MANUAL. AIRCRAFT WAS RELEASED FOR SERVICE.