A car's on-board diagnostics allow it to monitor the engine controls, chassis, body and transmission of the vehicle. The OBD system outputs trouble codes. A technician's ability to read those trouble codes and real-time statistics, such as mileage and speed, from the diagnostic panel of a car significantly improves the effectiveness of the repair process. The GM P0306 trouble code indicates engine cylinder problems and includes the misfired cylinder number of a car engine in the fourth digit of OBD code, cylinder No. 6.
Check all wiring and ignition components, such as the spark plugs, distributor cap and connectors, that lead to the engine cylinders, if the engine is faltering or stuttering when fired up. Replace faulty wires or plugs to repair the ignition system.
Replace the car coil pack, if inspection of the car ignition components did not resolve the engine firing problem.
Replace the catalytic converter, if you sense any malodor in the car exhaust.
