As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING DESCENT, SELECTED WING ANTI-ICE SWITCH ON AND L VALVE LIGHT ILLUMINATED. TURNED WING ANTI-ICE SWITCH OFF AND LIGHT WENT OUT. IT OCCURRED AS WE WERE DESCENDING THROUGH 9,000' FEET. GROUNDED - YES. REMOVED AND REPLACED L WING ANTI-ICE VALVE REF B737-9 AMM 30-11-11.