5 Symptoms of a Bad Steam Canister Vent Valve
Gasoline contains over 150 toxic chemicals. Inhaling the fumes can cause dizziness, headaches, and breathing difficulties, and prolonged exposure can be fatal. This is why federal law mandates technology like vent valve solenoids to reduce these harmful gases.
When a solenoid valve fails, smoke and exhaust gases are released unhindered. Learn the early signs of a bad steam tank vent valve and how much it might cost to replace it. What is a steam canister purge valve? The vapor canister purge valve is a component of a vehicle’s evaporative emissions system. The system itself is designed to minimize the amount of gasoline vapors released into the environment to meet today’s emissions standards.
Alternatively, the vapor canister purge valve is often referred to as the EVAP purge valve or charcoal canister purge solenoid. Whatever you call it, the function of this device is virtually identical on all vehicles, acting as a gatekeeper of sorts when it comes to controlling the flow and redirection of gasoline vapors.
Purpose
The vapor canister purge valve is an electrically controlled device that responds to ECM/PCM commands to redirect gasoline vapors into the vehicle engine for further combustion. When power is removed from this valve, the valve returns to the closed position, thereby capturing fuel vapors from the EVAP canister itself.
It is worth noting that most early EVAP purge valves were actually vacuum operated, not electrically powered as they are today.
Modern EVAP purge valves are typically placed in the “open” position during engine operation. If the vehicle’s ECM/PCM does not self-check for EVAP leaks, this valve will open when the vehicle’s engine is started. When ignition power is shut off, the purge valve closes again.
Location
In most applications, the vapor canister purge valve is located within the vehicle’s engine compartment, often very close to the engine’s intake manifold. In some cases, the purge valve is mounted directly on the intake manifold or rail itself.
Symptoms of a Failed Vapor Tank Vent Valve
A failed vapor tank vent valve is often associated with a number of underlying symptoms, some of which can be very problematic. Below are some of the most common of these symptoms.
1) Check Engine Light Illuminated
In most cases, a failed or defective fuel vapor vent (EVAP) valve will cause your vehicle’s check engine light to be illuminated. This light will come on when one or more applicable EVAP system DTCs, such as P0441 or P0442, are logged because the normal flow of fuel vapors is blocked.
2) Rough Idle/Slow Performance
A failed fuel vapor vent valve (EVAP) can cause a significant decrease in your vehicle’s performance. This type of performance loss is most noticeable at low speeds, but problems at higher loads are not unknown. Uneven or irregular idling is also commonly observed.
3) Difficulty Starting/No Starting Conditions
Another sign of a faulty EVAP purge valve is the inability to start the vehicle despite hard cranking, or a reluctance to start under the same circumstances. This is usually due to a rich/lean fuel condition, depending on what position the purge valve itself is stuck in.
Leaving the valve open can allow too much fuel vapor into the engine, creating a mixture that is too rich and difficult to ignite. On the other hand, if the valve is stuck closed, it can result in a lean condition that lacks the fuel needed for proper combustion. Either scenario can result in frustrating starting problems, even if the battery and starter are in good working order.
4) Reduced Fuel Consumption
A stuck or blocked control valve can result in a significant drop in fuel consumption. This is due to a distortion of the air-fuel ratio caused by unpredictable vapor distribution that is very different from what is expected by the vehicle’s ECM/PCM.
This fuel-air imbalance causes the engine to work harder and less efficiently, using more fuel than necessary to produce the same performance. This may result in more trips to the gas station.
5) Failed Emissions Tests
The vapor canister vent valve is a critical component of your vehicle’s EVAP system. Its failure often results in subsequent emissions tests not meeting requirements. If your vehicle has recently failed such a test, the vapor canister vent valve may be to blame.