Q: Getting code P0303

If you have already taken the first step of getting your codes scanned, the next thing to do would be to have an ignition test performed by a qualified technician. Attempting to do this yourself could result in being shocked by high voltage. This test would entail removing the ignition coil and placing the ignition tester in the circuit between the coil and the spark plug. If the spark plug or coil is faulty, the light will not flash consistently or at all on the ignition tester leading the technician to believe that either the coil or the plug is faulty for cylinder three. After confirming the lack of spark to cylinder three, the technician may erase your fault codes and switch your number three coil to the cylinder adjacent to it. When your Check Engine Light comes back on, if the misfire has switched to the other cylinder, the coil is faulty. If the misfire stays on cylinder three, the spark plug is faulty. If the spark plug is faulty, it is a good idea to have all spark plugs replaced at once.