Basic Information

English name: Activated charcoal canister
OEM:XXX 201 801
Note: It is often used in conjunction with an activated carbon canister solenoid valve

What is an activated carbon canister?

A carbon canister is a can filled with activated carbon, which is a device used to collect and reuse gasoline vapor. Gasoline is highly volatile, and the pressure inside the fuel tank will increase as it evaporates. To prevent danger, early fuel tank caps were designed as pressure relief valves. When the pressure inside the tank exceeds a certain value, the pressure relief valve opens, and gasoline vapor is directly emitted into the atmosphere. However, this results in gasoline waste and environmental pollution. Therefore, the Evaporative Emission Control System (EVAP) was later developed, and the activated carbon canister is an important component of this system.

The activated carbon canister is located between the gasoline tank and the engine pipeline. Its installation position varies from car to car. Some are mounted on the frame, while others are installed inside the engine compartment. How to find the activated carbon canister? A. Generally, there are only three pipes on the fuel tank, among which the fuel supply pipe and the fuel return pipe are related to the engine. Follow the remaining pipe to find the activated carbon canister. B. Alternatively, you can follow the pipe behind the throttle valve to locate it.

The function of the activated carbon canister is to collect fuel vapor from the fuel tank. Gasoline is volatile, and to prevent it from evaporating and creating pressure in the fuel tank, and subsequently escaping into the atmosphere, the vehicle is equipped with an evaporative emission control system (EVAP) that utilizes the physical adsorption effect of activated carbon. This system stores the gasoline vapor in the activated carbon canister, and under certain conditions, it passes through the canister solenoid valve and pipeline into the intake manifold to participate in combustion.

working principle

When the engine is operating, the ECU controls the opening and closing of the canister solenoid valve based on signals such as engine speed, temperature, and air flow, thereby regulating the vacuum level above the emission control valve and controlling its opening. When the emission control valve is open, fuel vapor is drawn into the intake manifold through the emission control valve to participate in combustion.

Note: Some vehicle models only have solenoid valves without control valves installed, and the opening and closing of the solenoid valve controls whether gasoline vapor enters the intake manifold to participate in combustion.

Precautions

Many friends may encounter the problem of difficulty starting the engine due to overfilling the fuel tank. This is likely due to a problem with the gasoline evaporation control system where the carbon canister is located. If the carbon canister solenoid valve is constantly open, it will cause all the gasoline vapor in the fuel tank to enter the intake manifold, which will make the computer detect that the mixture is too rich and thus unable to start. If the solenoid valve is constantly closed, it will cause the gasoline vapor in the carbon canister to become saturated, and the excess gasoline vapor will directly dissipate into the atmosphere, resulting in a strong gasoline smell inside the car and other issues.