i just order a new transmitter and i was told it would not be under warranty. the only way to get a warranty on it is to buy a starter kit from them which includes the transmitter and the receiver.
Actually I was informed of this before I even purchased my DexCom unit. Basically they told me the transmitter replacement is similar to having to buy new pump cartridges, infusion sets and pump batteries for those of us who use insulin pumps. It is an expendable. The reason for having to replace the transmitter is it contains a non-replaceable battery used to power it. Eventually the battery will died and you need to replace the entire transmitter to get a new battery. I was also told they do replace transmitters under warranty if they die prematurely.