The three most commonly viewed on-board diagnostic system II engine codes for Honda vehicles are P1456, P0420 and P1259. P1456 means evaporative emissions control system leakage fuel tank, P0420 is catalyst system efficiency below threshold bank 1, and P1259 is a variable valve timing and lift electronic control system malfunction.
The first character of an OBDII engine code identifies the vehicle system related to the trouble code. P stands for powertrain, B for body, C for chassis and U is undefined.
The second digit identifies whether the code is a generic code or a manufacturer-specific code. Zero indicates a generic code and 1 a manufacturer-specific code. Honda-specific engine codes are only available for powertrain malfunctions. All engine codes for body, chassis and undefined apply to all automotive makes.