As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ORD - FLT 4323 - DURING TAXI, CABIN BECAME HAZY AND HAD AN ODOR OF SMOKE. NO EMERGENCY DECLARED AND PASSENGERS DEPLANED NORMALLY AT THE GATE AREA. REPLACED NR 1 ENGINE P2.5 P3 SWITCHING VALVE. OPS CHECK GOOD. AIRCRAFT WAS RETURNED TO SERVICE. (X)