The Purpose of a Charcoal Canister

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The importance of controlling emissions from automobiles created the need for a refined and modified automobile system. The charcoal canister was developed with this goal in mind. It is a vapour holding device, used for the evaporative control system (EVAP) that captures any raw fuel evaporating from the fuel storage system, like the fuel tank or the fuel cap, of a motor vehicle. You will be able to locate the charcoal canister near the fuel tank or in the engine compartment.

EVAP & Charcoal Canister

The evaporative control system functions in such a way that the charcoal canister not only captures and stores but also purges raw fuel vapours. It stores any leaking fuel tank vapours or raw hydrocarbons that would otherwise escape and pollute the atmosphere. The operating conditions of the EVAP, which change according to the engine temperature, speed and load help these captured fuel vapours to be put back into the combustion process.


The charcoal canister, which is the vapour-holding gadget for the EVAP System, is a plastic enclosure that contains a large piece of activated charcoal. Activated charcoal is a form of charcoal that has been treated with oxygen to increase its ability to absorb fuel vapours by opening up tiny pores between the carbon atoms present in charcoal. The charcoal canister must be tested daily for its vapour-holding ability as it is subjected to moisture and temperature changes. Increase or decrease in moisture and temperature affects its vapour-holding ability.


Charcoal canisters are essentially created to decrease the amount of air pollution the vehicle creates and also increase its fuel efficiency. The charcoal canister traps and absorbs fuel vapours from the fuel tank and the carburettor of a motor vehicle when the engine is not running. When the engine is running, the fuel vapours in the canister are absorbed through a vacuum hose into the intake manifold and put back into the system.

Charcoal Canister Absence

Without the presence of a charcoal canister, the excess fuel vapours would collect beneath your vehicle and emanate a strong smell of fuel, apart from allowing unfiltered air to enter the engine. If your vehicle is running on an unpaved or dirt road, dust particles could enter the engine causing abrasion and other damages and eventually resulting in costly repairs to your vehicle.

Charcoal Canister Maintenance

Charcoal canisters do have a tendency of clogging up due to the accumulation of large amounts of dust and impurities from the air, which reduce the performance efficiency of the canisters. After a certain period of time, the canister will stop functioning and will have to be replaced. The replacement should be done only by a qualified professional, at a reputable garage, who would be aware of the risks involved if it is done incorrectly.

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