I've cleared emmission code by dumping 3 cans of Berrymans chemtool. Unplug your battery to reset the code. If they plug in at this point, the computer will not be in the "ready mode" and you will fail. Each car has a certain mix of different types of driving to make it ready (drive 30mph x certain amount of time, repeat, idle 5 minutes, 5 start and stop cycles, you get the idea). Look your cycle up, each car might be different. When you're done, smog it immediately.