As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EWR---CO3181, CREW REPORTED, "AIR RETURN DUE TO LDG AIR GND FAILURE AND THRUST REVERSER #1 DISAGREE" MESSAGES AFTER ROTATION. RUMBLING HEARD FROM NOSE ON CLIMBOUT. MAINTENANCE SERVICED THE NOSE LANDING GEAR STRUT AND REMOVED AND REPLACED NOSE LANDING GEAR PROXIMITY SWITCH. TEST FLEW AIRCRAFT SATISFACTORY. AIRCRAFT RETURNED TO SERVICE.