As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT DUCT LEAK LIGHT ILLUMINATED AFTER TAKEOFF. APU BLEED ON, ENGINE BLEEDS OFF. STARTED QUICK REFERENCE HANDBOOK PROCEDURE, LIGHT WENT OUT. RETURNED TO AIRPORT. FOUND BROKEN SOLDER JOINT ON LEFT PACK DUCT LEAK SENSOR NEAR BLEED AIR CONTROL VALVE. RESOLDERED WIRE. LEFT PACK OPS CHECKED GOOD.