What was found
AFTER NORMAL TAKEOFF AND COMPLETING AFTER TAKEOFF CHECKLIST WE WERE CLIMBING THROUGH 11,000' WHEN WE RECEIVED A CAUTION AND LE FLAP DISAGREE EICAS MESSAGE WITH BOTH FLAP INDICATORS SHOWING BETWEEN UP AND 1. A FEW TIMES THEY MOMENTARILY RETURN TO UP BUT THEN RETURN TO BETWEEN UP AND 1 WHERE IT EVENTUALLY STAYED. COMPLIED WITH QRH, DECLARED AN EMERGENCY AND COMPLETED AIR-TURNBACK. REMOVED & REPLACED LEADING EDGE SLAT SENSOR S294 #12 OUTBOARD. REF. AMM 27-88- 01-2. OPS CHECKS GOOD. NO DEFECTS NOTED.