As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 2131 - BOS-LGA - EMERGENCY LANDING - THREE LOUD BANGS WERE HEARD WITHIN TWO MINUTES BELOW LEFT WING AND VIBRATION WAS FELT AT FLIGHT LEVEL 16000. CAPTAIN DECLARED EMERGENCY AND RETURNED TO BOSTON. AIRCRAFT LANDED NORMALLY AND TAXIED TO THE GATE. REPLACED LEFT ENGINE DUE TO COMPRESSOR STALLS. NO FAULT FOUND. ENGINE RESTORED AND TESTED.