As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SHORTLY AFTER DEPARTURE FROM IAH, EB127/796FT AIR RETURNED TO IAH DUE TO NR 4 FIRE WARNING. REPLACED O/B LOOP ASSY ON LOWER FAN CASE, ADJUSTED WIRE BUNDLES NEXT TO START VALVE DUCT. RAN ENGINE NO MALFUNCTION FOUND. DID BLEED AIR LEAK CHECK. NO LEAK NOTED. RAN FIRE WARNING AND LOOP SHORT CHECK, ALL NORMAL. OK FOR SERVICE.