As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FIRE/OVHT DETECT LOOP B INOP ON #2 ENGINE. GROUNDED - YES. PERFORMED ENGINE/APU FIRE DETECTION BITE REF B737-800 FIM 26-10 TASK 801. FOUND #2 ENGINE FAN UPPER DETECTOR FAULT. REMOVED AND REPLACED #2 ENGINE FAN DETECTOR HARNESS FOR CHANNEL B (MW0316) IAW B737-800 AMM 26-11-02/401. GROUND VERIFICATION TEST IS GOOD. NO FAULTS ON ENGINE/APU FIRE DETECTION BITE. THIS CLEARS MEL 26-2B.