[KennyP]

If you want to determine which coil exactly is faulty then yes you need some sort of code reader...
i guess for engine codes it doesnt have to be anything fancy... but if you want to scan cars other systems/ modules and their errors then you will need something more specific...

but yet again... if you replace all 6 now preventatively then you will not have problems with coils for a long time and you dont even need to determine which coil is acting up etc... so basically you dont even need to spend money on a code reader...

Others can recommend code readers better... i myself use Cobb Accessport for that... its main function is to flash custom maps to the ecu... stage1 up to stage2+ for example, but it also can read and delete engine error codes, reset adaptations, monitor live data like boost pressure, fuelpressure, intake air temp, coolant temp, air-fuel ratios. It can also datalog but i have never really used this feature... you can also do performance testing with it.. like measure 0-60mph time or 1/4 mile time, though its accuracy is a bit questionable...

but i guess you can read and clear engine codes with things like Carly app and its bluetooth obd dongle for example.. or get something from car parts store...

To determine if its a specific coil that is faulty and which one... you swap coils from cylinder to cylinder and see if the code follows...