When i switched to Dreamscience i kept my Bluefin unit for fault finding, Mine always says that it is unable to clear all codes. this is normal. I dont know what 1218 is, its not listed on the DTC Codes i have?
Usually a fault on the ST170 will be a common one, so its worth checking them all, IMRC unit, cable and check the level itself is intact, fuel pumps fail, both lambdas fail but only the front one effects the running of the car. Coil pack, and of course clutch.