Vapor Canister Vent Solenoid Buyer's Guide
- A canister purge valve or solenoid is connected to the vapor canister and engine vacuum. It siphons a certain amount of fuel vapor out of the canister through the engine intake vacuum.
- If the vapor canister vent solenoid fails or malfunctions, it is usually due to dirt and dust from daily driving. Harsh conditions on the road can also cause the valve or solenoid to crack.
- Problems with the signal, circuit, position, and overall condition of the vapor canister vent solenoid can set off the check engine light and lead to pressure buildup in the fuel tank, increased vehicle emissions, rough idling, hard starting, and poor engine performance.
- The price range for a vent solenoid replacement is around $20 to $160. It is sold per piece, as a kit, or as a complete assembly, depending on the configuration of your vehicle.
Noxious gases do not only come out of the tailpipe. They also evacuate the fuel tank as fuel vapor that contains different types of hydrocarbon. That is why since the 1970s, the EPA (US Environmental Protection Agency) has required gasoline-powered vehicles to be equipped with an EVAP (Evaporative Emission Control) system.
This system keeps dangerous amounts of fuel vapor from getting into your vehicle and being released into the atmosphere. After all, evaporated fuel doesn't just pollute the air as toxic car emissions. When inhaled, this can also cause headaches, breathing difficulties, and nausea.
If there is any break in the vent lines or fault in the system, say, a malfunctioning vapor canister vent solenoid, the EVAP will not be able to keep the gas fumes from leaking out.
What Is a Vapor Canister Vent Solenoid?
The EVAP system mainly consists of a vapor canister, hoses, and valves. Aside from purging the fuel tank of potentially harmful fuel vapor, the system vents out the fumes into the engine, where it is burned with the rest of the air-fuel mixture.
Passing through the vent lines, excess gas fumes from the fuel tank are stored in the canister, which is filled with activated carbon pellets much like a charcoal filter. Similar to a sponge, the filter absorbs excess gas fumes from the fuel system and the fuel tank when the engine is off. When the engine is running, the collected fuel vapor is routed back to the fuel system and into the combustion chamber.
A canister purge valve or solenoid is connected to the vapor canister and the engine vacuum. Through the vapor canister vent solenoid, a certain amount of fuel vapor is siphoned out of the canister through the engine intake vacuum and taken into the engine intake manifold. This cycle greatly reduces car emissions and increases fuel efficiency by re-using the fuel vapor and recycling the gas fumes.
How Does a Vapor Canister Vent Solenoid Work?
The canister purge valve or solenoid is electrically operated by the engine computer or a control unit. The engine computer activates the solenoid when the engine is running, opening the valve to draw out the vapor through the vacuum and venting it out into the engine for combustion. This also deactivates the solenoid when the engine is off, closing the valve as the vapor from the fuel tank is trapped in the canister.
If the solenoid is malfunctioning due to electrical problems, the engine computer can trace it through EVAP system monitoring. This can determine whether or not the valve is using the engine vacuum properly. If there is any issue with the vapor canister vent solenoid, this will set off a trouble code and illuminate the check engine light.
Where Is the Vapor Canister Vent Solenoid Located?
EVAP system setups and configurations vary across different makes and models. The vapor canister vent solenoid may be installed on the front or at the rear.
Depending on the type of vehicle, the vent solenoid can be situated somewhere in the corner of the engine compartment, particularly on the engine intake next to the throttle body. It can also be found on the driver’s side near the rear quarter panel. More specifically, this can be set behind the fuel tank. A vehicle owner’s manual can be your guide to finding out the exact location of this EVAP system component.
What Causes the Vapor Canister Vent Solenoid to Fail?
When the vapor canister vent solenoid fails or malfunctions, it is usually due to a pile of dirt and dust from daily driving. This can clog the vapor canister as well as the vent valve or solenoid. The foreign particles and debris can be drawn from the vent hose, which causes the eventual blockage of the valve.
Harsh conditions on the road can also ruin the valve or solenoid. Because of these, the canister and the valve or solenoid may crack. Aside from cracking or getting clogged, the valve is also prone to being stuck open or closed.
Once the valve or solenoid is broken, this can cause a leak and can also ruin other components in the EVAP system. This will trigger the check engine light on the dashboard to come on and will display some trouble codes to alert you of the problem with the system.
The electrical issue with the solenoid can be checked or confirmed through a tester or a scan tool. Once a fault is detected with the solenoid, this typically requires a replacement and, sometimes, some modifications on the vent valve.
What Are the Most Common Vapor Canister Vent Solenoid Symptoms?
The engine computer can detect problems with the signal, circuit, and position of the vapor canister vent solenoid. Here are the telltale signs of a bad vapor canister vent solenoid:
Pressure buildup in the fuel tank
A faulty vent solenoid will not be able to release pressure from the fuel tank. As a result, the pressure will build up and may only escape once the fuel tank is opened.
Increased vehicle emissions
A bad vent valve or solenoid, or practically any faulty part in the EVAP system, can be the reason why the vehicle may fail the emissions test. The broken solenoid will bring about vacuum leaks or will fail at redirecting the fuel vapor to the engine for combustion. This will get in the way of the usually smooth operation of the EVAP system.
A stuck-open valve or malfunctioning solenoid can cause rough idling. The vehicle will not be running smoothly, especially at low speeds, because of the vacuum leak.
A vacuum leak due to a bad solenoid or broken valve will make it difficult to crank up the engine. When outside air gets into the engine, this can mess up the air-fuel ratio in the cylinders and affect the internal combustion process. As vapor builds up inside the canister, this can also result in stalling or misfiring.
Poor engine performance
A damaged solenoid or defective valve can also make it difficult for the engine to meet the higher demands for horsepower and torque, especially when accelerating. As fuel infiltrates the canister, the engine may also choke.
How Much Does a New Vapor Canister Vent Solenoid Cost?
The price range for a vent solenoid replacement is around $20 to $160. The solenoid is sold per piece, as a kit, or as a complete assembly, depending on the configuration of your vehicle. When buying a replacement, make sure that this is compatible with your vehicle. For that, check the connector, terminal, and other features.