Common Symptoms of a Fault Evaporative Emissions (EVAP) Canister

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The Evaporative Emissions (EVAP) system is a closed-loop system designed to capture smog-forming fuel vapors and prevent them from polluting the atmosphere. Instead of allowing these vapors to contribute to air pollution, the EVAP system harnesses them to aid in powering the engine. A key component of this system is the EVAP canister, which stores fuel vapors until the purge valves open. This allows the engine to absorb the fuel vapor from the fuel tank into the intake manifold. However, if the EVAP canister malfunctions, fuel vapor can escape into the environment, leading to pollution. This can also result in reduced fuel efficiency and poor engine performance.

This article highlights the common symptoms of a faulty EVAP canister, helping identify potential problems and their underlying causes.

What Causes Evaporative Emissions (EVAP) Canister Failures?

Physical Damage: Physical damage to the EVAP canister can occur due to vibrations, exposure to high pressure, temperature, improper installation, or corrosion. These conditions can affect the performance and lifespan of the EVAP canister and prevent it from functioning properly.

Contamination: Contaminants (such as dirt, debris, etc.) can accumulate in the canister and cause restrictions that reduce the flow of fuel vapor from the fuel tank to the combustion chamber.

Neglecting Regular Maintenance: Failing to perform regular maintenance, such as cleaning the EVAP canister air filter or replacing the canister, causes it to clog, leading to failure.

Wear and Tear: Over time, regular usage can lead to the gradual wear of the canister’s components.

Common Symptoms of a Faulty Evaporative Emissions (EVAP) Canister

Malfunction Indicator Light (MIL) or Check Engine Light (CEL) Illuminates

The Powertrain Control Module (PCM) monitors operation of the emission-related systems in your vehicle. If something goes wrong, it stores a Diagnostic Trouble Code (DTC) and illuminates the MIL on your dashboard to alert you. This is precisely what occurs if the EVAP canister is not functioning properly. To identify the exact reason the MIL is on, use an OBD2 scan tool to retrieve any stored DTCs and Freeze Frame information to determine the root of the issue. This will help you understand what’s going wrong and take the necessary steps to correct it.

Difficult to fill up the fuel tank

The EVAP canister is an essential component of the EVAP System that helps to prevent fuel vapor from escaping into the atmosphere. If the canister becomes clogged, the fuel vapor will not be able to pass from the fuel tank to the canister. This will lead to a build-up of pressure inside the tank, causing issues while refueling. If you experience such issues, it is likely due to a clogged EVAP canister.

Fuel Smell Odor

If the EVAP canister is damaged, it leads to fuel vapor being released directly into the atmosphere instead of being stored and processed through the EVAP system as designed. This fuel vapor has a distinct odor that can be detected when the engine is running and even when it’s turned off. So, if you notice a strong fuel odor coming from your vehicle, whether it’s running or not, it’s a good idea to start your troubleshooting process with the EVAP canister.

Decreased Fuel Economy

Your vehicle is designed to make the most of its fuel, even using the vapors that form in the tank. When the EVAP canister fails, you will lose some of the fuel usually used during combustion, which will reduce your vehicle's fuel efficiency.

Identify A Faulty Evaporative Emissions (EVAP) Canister with the Innova Scan Tool

The Innova Scan Tool is an extremely useful diagnostic instrument designed to swiftly pinpoint issues within a vehicle’s systems. It aids in identifying and correcting problems related to the EVAP Canister by retrieving stored DTCs, the I/M Status of the vehicle, and any Freeze Frame data from the vehicle’s computers. This tool effectively aids in diagnosis of EVAP Canister-related issues in vehicles, helping you to accurately identify and resolve problems with ease.

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