Bruce: this is not intended to provide you with the accurate explanation; someone who knew the chip will respond. I was told when I bought mine that the chip was pulled becuase of the color. If you go to TCR you will see and explanation.. They list the yellow $2.50 in two places, giving it the same N6439 # but list the canceled one as an "E" rated chip and the non-canceled one as an "M." It sounds like yours is uncanceled.