1996 Plymouth Voyager fuel injector circuit

I would just like to ask if the fuel injector and the circuit are one in the same? Service engine light is on, the message from the computer reader is; cyl. 2 fuel injector circuit malfunction. Does the whole injector have to be replaced, or are there faulty wires, (perhaps an exposed wire that would be shorting out)? You can feel it going in and out by way of engine power. Sometimes it does work. Any response would be most appreciated. Thank you so much for your time!