What was found
#2 COWL VALVE OPEN LIGHT STAYS BRIGHT (VALVE NOT OPENED). GROUNDED - YES. ACCOMPLISHED INSP OF O/P SWITCH S806. NO FAULTS FOUND. REF FIM 30-21 TASK 801. DUE TO PR REG #2 ANTICE VLV R2. PER PILOT VERBAL: 20K PASSING THROUGH ICING CONDITIONS FOR ABOUT 5 MIN. LIGHT STAYED BRIGHT FOR REMAINING OF THE FLIGHT AND TAXI IN. DIFFERENT POWER SETTING MADE NO DIFFERENCE. AS PRECAUTION REMOVED AND REPLACED #2 ENGINE COWL TAI VALVE. OPS CHECK AND LEAK CHECK GOOD. REF AMM 30-21-11/401.