As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
TURNED WING ANTI-ICE ON IN FLIGHT IN 'ICING CONDITIONS. MASTER CAUTION L VALVE ILLUMINATED, TURNED WING ANTI-ICE OFF AND LIGHT EXTINGUISHED. GROUNDED - YES. PERFORMED MAX WING ANTI-ICE VALVE HEALTH CHECK REF MAX-30EA-24968. NO FAULT NOTED.