As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW NOTICED SMOKE IN THE COCKPIT AND RETURN TO DEPARTURE. MX TROUBLESHOTING FOR SMOKE IN COCKPIT IAW FIM 21-20-00-816-801-A. SMOKE AND HAZE APPEARS WHEN THE NR 1 PACK WAS SELECTED ON. NR 1 PACK WAS NOTED ON THE EICIAS OUT OF EWR AND MESSAGE CLEARED RESET PACK 1 AND MESSAGE CLEARED. PERFORMED ENGINE RUNS IAW MM 71-00-01. NO ODOR OR HAZE NOTICED AS LONG AS PACK WAS NOT SELECTED.