1. This OBD fault code is applicable to all car manufacturers' models: P240 1. Control circuit of leak detection pump in fuel evaporative emission system. Evaporative emission system leak detection pump control circuit Low category: Detailed meaning of emission control: Evaporative emission (EVAP) system introduces gasoline vapor from fuel tank to storage tank filled with activated carbon, which can absorb gasoline vapor. Then, the engine will use fresh air to blow gasoline vapor into the engine combustion chamber. The function of the leak diagnosis module is to apply less pressure to the evaporative emission (EVAP) system and the fuel system through the leak detection pump (LDP), and then detect whether there is a leak in the system to ensure that no harmful steam escapes into the atmosphere.