e1ght4vii

i have a 91 honda accord lx with 240k miles on it when i did the shift cable i couldnt get the shifter off with the sport mode switch on it so i cut the wire and replaced it ever since then my s light on my dash has been blinking. recently i feel like my gas mileage has gone down so i put a jumper on the terminals to make the code flash on the dash and my engine light doesnt flash although my S light looks lights its flashing 3 code 1,3, and 15 what could this be?