check engine light on after fuel injection cleaning; what needs to be done?

After fuel injection cleaning, car drives with hesitation and shakes as if its going to stop. Check engine light is on -- scanner indicated sensor in exhaust. Used premium gas hoping that would stop the shaking -- no such luck. Would this be the o2 sensor? and does it cause the car to behave that way because of the o2 sensor? or is this something else entirely. All I know is once they used the fuel injection cleaner, problems began to occur.