What was found
CREW REPORTED LEFT WING ANTI-ICE CAUTION MESSAGE AFTER TAKEOFF POWER ADDED. CREW ABORTED TAKEOFF AND RETURNED TO GATE. MAINTENANCE INSPECTED AND DEFERRED WING ANTI-ICE NORMAL MODE PER MEL. ON NEXT FLIGHT, LEFT WING ANTI-ICE AMBER CAUTION MESSAGE WOULD NOT EXTINGUISH IN STANDBY MODE BEFORE TAKEOFF. CREW RETURNED TO GATE. MAINTENANCE REMOVED AND INSPECTED LEFT WING ANTI-ICE SHUTOFF / MODULATING VALVE, CLEANED VALVE AND PRSOV (PRESSURE REGULATING / SHUTOFF VALVE) FILTER, RE-INSTALLED VALVE, PERFORMED CHECKS AND CLEARED DEFERRAL USING AIRCRAFT MAINTENANCE MANUALS. AIRCRAFT RELEASED FOR SERVICE.