As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON TAXI-OUT, CREW REPORTED A PUNGENT ODOR THAT WAS EVIDENT IN AFT CABIN AND COCKPIT WITH PACKS ON. FLIGHT RETURNED TO THE GATE. MAINTENANCE ACCOMPLISHED J/C 26L00021001 AND 99L21005001. FOUND EXCESSIVE LUBRICANT ON LEFT PACK INLET DOOR ACTUATOR FROM PREVIOUS NIGHT OF PACK WORK. CLEANED AREA AND REPLACED RECIRC FILTERS PER AMM 21-21-41. OPS CHECKED BOTH PACKS. NO ODORS EVIDENT AT THIS TIME.