Check engine

You can tell the severity of the diagnostic fault code by how the Check Engine light acts. The most severe problems are when the light is flashing. That means stop the engine right away because too much unburned fuel is going into the exhaust system where it is going to burn in the catalytic converter and damage it.

Rather than replace random parts, a better approach is to swap the coil for cylinder # 2 with one of the other ones, lets say cylinder # 3, and the injector with the one from cylinder # 4. Erase the fault code, drive the vehicle, then see if a code sets for cylinder 2, 3, or 4. That will tell you if the coil, injector, or something else is suspect.