What to know about the Evaporative Emission Control Canister:
Have you ever been around a vintage or classic car that exhaled a raw fuel odor, yet no leaks were apparent? Gasoline vapors are very noxious if inhaled; they contain damaging chemicals such as benzene and toluene, which can cause headaches, nausea, and breathing problems. Vehicle manufacturers are needed to limit the amount of fuel vapors that can be emitted from a vehicle. The evaporative emissions system consists of a charcoal canister, valves, hoses and a sealed fuel cap.
When fuel vapors are generated inside the fuel tank due to evaporation, they are collected inside the charcoal canister, or evaporative emission control canister. At a time determined by the engine control module, the fumes collected in the charcoal canister are purged through a valve and sent into the engine to burn as part of the air/fuel mixture. Dust and dirt from frequent driving situations can accumulate on the emission control canister, causing the purge and vent solenoids or valves to malfunction. It is also possible for the charcoal canister itself to crack either due to impact or harsh environmental conditions. When this occurs, raw fuel or fuel vapors are lost into the environment around your vehicle, and a noticeable fuel smell can occur.
Facts to Note:
Many evaporative emissions-related Check Engine light codes are caused by a loose or leaking fuel cap.
How to Fix:
The evaporative emission control canister is defective and requires replacement
The faulty canister is detached
The new canister is installed
The engine is scanned for codes
The vehicle is road tested for correct operation and no check engine light comes on.
Though regular maintenance or scheduled replacement is not necessary, the charcoal canister can become clogged from moisture or contaminants in the fuel. If the charcoal canister is damaged and leaking, or if a diagnosis determines the charcoal canister or one of its parts is in charge of a Check Engine light illuminating, have the evaporative emission control canister changed by one of your expert mechanics.
Common symptoms indicating you may need to change
Check Engine light is on
Raw fuel smell from the back of your vehicle near the fuel tank
Importance of this service:
If the evaporative emission control canister is not changed when it is diagnosed, other problems with your vehicle may go undetected as the Check Engine light will illuminate for dozens of other reasons. Because fuel vapors are harmful to inhale, and a fuel leak can cause a fire, you should change the charcoal canister as soon as you can.