As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UPON PERFORMING EEC TEST ON ENG #1 FOUND FAULT CODES 73-21281 AND 73-20101. GROUNDED - YES. REMOVED #1 ENG EEC AND REPLACED WITH SERVICEABLE UNIT THROUGH REF B737-800 AMM 73-21-60/401. INSTALLATION TESTS COMPLETED & ALL TESTS PASSED. NO FAULTS.