Content Addressable Memories (CAM) are widely used for the tag portions in highly associative caches. Since data are not explicitly read out of tag array in CAM search, the detection of false misses caused by soft errors for such caches, is difficult. This paper presents a technique to detect the false miss in highly associative cache with CAMbased tag. The technique involves subdividing the tags and providing backup checking for cases the tags are partially matched. An original tag encoding scheme is proposed to reduce the frequency of back-up checking. Modifications to support the technique do not increase the cache access latency. The performance degradation incurred by additional cycles for false miss checking is very low.