As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON TAXI OUT ENGINE CONTROL LIGHT ILLUMINATED #1 ENGINE. GROUNDED - YES. ACCOMPLISHED EEC BITE FOUND FAULT 75-20581 (TBV DEMAND AND POSITION SIGNALS DISAGREE). ACCOMPLISHED ACTUATORS TEST NO CURRENT FAULTS NOTED. ENGINE CONTROL LIGHT EXTINGUISHED. REF B737-800 FIM 73-00 TASK 801 AND FIM 75-23 TASK 801.