As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE CREW REPORTED A ACRID FOG IN COCKPIT WHICH OCCURED SIMULTANEOUSLY WITH THE LAVATORY SMOKE ECIAS MESSAGE. FOG NOT SMOKE BUT WAS HIGHLY VISIBLE AND VERY PUNGENT. ACFT RETURNED TO DEPARTURE AND LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE INSPECTED AND REPLACED THE NR 1 ENGINE. CARBON SEAL DAMAGED. OPS CHECKED LAV SMOKE DETECTOR, GOOD.