Some of the most common automobile diagnostic error codes are P0420, P0174, P0455 and P0128, according to AA1Car.com. These error codes indicate specific problems with your car, which makes them easier for a mechanic to repair.
Each code suggests a specific automobile malfunction. For instance, the error code P0420 suggests that there is reduced efficiency in the catalyst system. The P0401 error code indicates insufficient exhaust gas recirculation flow, and P0455 is a detection of a leak in the evaporative emission system, as noted by AA1Car.com. The most common trouble codes suggest that the most common cause of a diagnostic test fail is a worn-out catalytic converter. The evaporative emission system, fuel trim, catalytic converter and engine are some of the most common systems that fail in an automobile.
There are several possible causes for a malfunction inside a car. For instance, a loose or cracked fuel tank hose may cause the P0442 error code, and a technician must find the leakage to solve this problem, according to AA1Car.com. P0300 indicates that there is a random misfire in the engine, usually caused by a lean fuel mixture or vacuum leaks. Codes narrow the troubleshooting area for technicians, thereby simplifying their work.