As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
#1 ENG "A" LOOP INOP. GROUNDED - YES. CONFIRMED FAULT, #1 ENGINE A-LOOP WILL NOT TEST. FOUND R/T CORE FIRE DETECTOR HARNESS (MW0315) TERMINAL LUG BROKEN AT THE DETECTOR, TOO SHORT TO REPAIR WIRING. REMOVED & REPLACED MW0315 CORE FIRE DETECTION HARNESS (A-LOOP) REF B737-800 AMM 26-11-02, OPS CK NML REF AMM 26-11-00-710-801. AIRCRAFT RELEASED FROM MEL 26-2B, C/N 03023587. REPOSITIONED #1 ENGINE OVHT DET SWITCH BACK TO NORMAL.