As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WING ANTI-ICE "L VALVE " LIGHT AND ASSOCIATED ASYMMETRIC WING ICE ON DESCENT. GROUNDED - YES. ACCOMPLISHED WING-ANTI-ICE VLV CHECK AND PERFORMED AN OPERATIONAL TEST ON THE WING-ANTI OPEN/CLOSED AFTER INTRODUCE PNEUMATIC SYSTEM OPS CHECK GOOD. ETOPS SIGNIFICANT GROUND TEST OPS CHECK GOOD. IN REF. TO AMM 30-11-00.