As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT COWL VALVE OPEN LIGHT REMAINS ON BRIGHT WHEN #1 ENG ANTI ICE SELECTED ON. WHEN SELECTED OFF, LIGHT EXTINGUISHES. GROUNDED - YES. VERIFIED COWL OPEN & TRANSIT LT WORKS OK WHEN JUMPERED @ DP1303. REF B737-800 WDM 30-21-11-10. REMOVED AND REPLACED #1 ENG TAI VALVE REF B737-800 AMM 30-21-11. OP CHECK GOOD NO LEAKS NOTED.