This device is not generally well known to the general public, but it performs a fundamental function, controlling emissions that are harmful to the environment and improving fuel efficiency.
What is the canister?
The canister is a component that is connected to the fuel line coming from the fuel tank. It is usually rectangular in shape, although others are also cylindrical in shape. It contains activated carbon inside.
What is the function of the canister?
The canister has two main functions: the first is to capture gasoline vapors produced in the fuel tank from being released into the environment, generating air pollution. It also has the function of improving fuel efficiency, since by capturing the vapors, they are recondensed and returned to the fuel tank so they can be used in the combustion process.
History and evolution of the Canister
Due to the widespread use of automobiles in the 1960s and 1970s and the growing concern about the environmental impact of cars, environmental regulations in the United States established by the Environmental Protection Agency (EPA) increased standards and requirements, forcing car manufacturers to implement solutions to mitigate the environmental pollution generated by vehicles. The canister evolved and to this day is a fundamental part of the emissions control system. Currently, many vehicles have sophisticated canisters with sensors connected to the ECU that controls fuel injection. When the canister fails, a Check Engine light alert is generated to warn the user of the fault, which is revealed by running a scan on the car.
Faults that the Canister may present
While the canister is a component that rarely fails, the most common failure is overfilling the fuel tank. When the tank becomes saturated, it loses efficiency in retaining and condensing fuel vapors. Another failure is the obstruction of the vapor lines by dirt or residues that can be present in the fuel, such as impurities.
OBD2 fault codes associated with the canister
Fault codes associated with the canister typically begin with P04xx, indicating problems with the evaporative emission control (EVAP) system. Common codes include:
- P0443: Canister Purge Solenoid Circuit Malfunction.
- P0456: Small Leak Detected in EVAP System.
- P0442: Small Leak in EVAP System.
- P0455: Large Leak in EVAP System.
- P1457: Leak Detected Near Canister Area.
Common causes of failure:
Leak in the hoses: Cracked, disconnected, or damaged hoses.
Blocked purge valve: Dirt or internal faults preventing proper operation.
Electrical failure: Problems with the canister purge solenoid valve.
Overfilling the fuel tank: Can saturate the activated carbon in the canister.
Symptoms of canister failure:
- Gasoline smell inside the vehicle.
- The “Check Engine” light appears on the dashboard.
- Emissions test failure.
