As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ORD - FLT 5708 - 'CHECK HEADING' ILLUMINATED IN FLIGHT BOTH NAV DISPLAY UNITS REMAINED ILLUMINATED WITH HEADING DIFFERENCE EXCEEDING 65 DEGREES. MAINTENANCE REMOVED AND REPLACED NR 1 MAGNETIC SENSOR UNIT AND PERFORMED COMPASS SWING. SYSTEM CHECKED SATISFACTORY. (M)