how do i fix my TCC. and where is it. i got a check engine light with the code of (P1864). by the way i have the OBD2. my cars timing is of. i just got a ne w computer installed. and all the sensors are brand new. it didn't start missfiring until after i drove it through a car was. and the code (P1864) didn't star popping up until i put the new computer. So what is going on?