As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ENGINE COWL VALVE OPEN LIGHT REMAINED ON AFTER #1 ENGINE COWL ANTI ICE SELECTED ON. GROUNDED - YES. REMOVED AND REPLACED THERMAL ANTI-ICE VALVE ASSEMBLY, REF B737-900 AMM 30-21-11-000-801 AND AMM 30-21-11-400-801. OPS AND LEAK CHECK GOOD.