As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON DESCENT WITH ENGINE ANTI-ICE SELECTED ON AND BOTH COWL VALVE OPEN LIGHTS ILLUMINATED DIM #2 ENG TAI ON ENGINE DISPLAY REMAINED ILLUMINATED AMBER. GROUNDED - YES. REMOVED AND REPLACED #2 ENGINE COWL TAI VALVE IAW B737-800 AMM 30-21-11 OPS CHECK GOOD. ETOPS GROUND VERIFICATION SUCCESSFUL.