The Evaporative Emissions Control System (EVAP) removes the excess fuel vapors from the tank. This process is critical, otherwise, the vapors would escape into the atmosphere. This system reduces the vehicle’s emissions to prevent the fuel from escaping into the atmosphere.
Once the engine starts, the bleed valve opens, allowing fuel vapor to be drawn through the vacuum created by the engine into the intake manifold. At the same time, the vent shutoff valve also opens, allowing a quantity of air to flow into the canister and mix with the fuel vapor. Once this process is complete, venting is achieved in the system, and the two valves close.0
The valve voltage is monitored by the Powertrain Control Module. If it is found a voltage below the manufacturer’s voltage setting, the DTC P0458 OBD2 will be set.