Code 15

My car starts. SHortly there after as soonas it gets warmed up it cuts out. I asked a few people about it and they thought it may be the heat sensor in the fuel system. When i inspected the ECU i got a one long 5 short (15) read out. That says ignition system. That leads me to believe that the coil is cutting when it gets hot. What do you think. links or comments please.