As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT ENGINE DUCT LEAK LIGHT ILLUMINATED INFLIGHT. SHUTDOWN LEFT ENGINE PER QRH PROCEDURES AND RETURNED FOR LANDING. PERFORMED EXTENSIVE GROUND RUN AT HIGH POWER SETTINGS, DUPLICATED DISC ISOLATED FAULT TO PRESS REGULATOR VALVE IN LEFT WING. INSTALLED SERVICEABLE VALVE. PERFORMED EXTENSIVE GROUND RUN AND NO LIGHTS OR LEAKS NOTED. OPS CHECKS GOOD.