As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHEN SELECTING WING ANTI-ICE, THE LEFT WING ANTI-ICE VALVE AMBER LIGHT REMAINED ILLUMINATED AND THERE WAS A 15 PSI DUCT SPLIT. GROUNDED - YES. REMOVED AND REPLACED LH WING ANTI-ICE VALVE REF B737-9 AMM 30-11-11 OPS CHK GOOD. GROUND VERIFICATION SUCCESSFUL. ORIG SUBMISSION DATE: 10/31/2022