Methods and systems for auto detecting and auto switching antennas in a multi-antenna FM transmit/receive system are disclosed and may include detecting when an external antenna may be coupled to an external port of the wireless device and utilizing the external antenna for transmitting and/or receiving FM signals. The decoupling of an external antenna from an external port may be detected, which may cause the FM radio transmitter/receiver to be configured to transmit and/or receive FM signals utilizing antennas internal to the wireless device. One or more test signals, which may include AC signals, may be generated within the chip for detecting whether an external antenna may be coupled to an external port. A reflected signal from an external port may be measured and compared to a prestored value corresponding to a reflection due to an open circuit at the one or more external ports of the wireless device.