I read my dtc's so i could clear a faulty o2 sensor code and this one popped up. It read B2215 fcm internal. What does this mean? Everything works on the truck. or at least i havent come across anything not working. I found it shortly after i took off the Transmission line booster mod wire. It also threw codes. Some i remember were "incorrect 4th gear ration","low line pressure" not sure if that had anything to do with FCM internal code.. it keeps coming back after i drive it for a day.