The adsorber valve carries out the process of regeneration of evaporation, otherwise called the system
(Evaporative Emission Control), which is controlled by a solenoid valve. When the adsorber becomes unusable, your car is not able to pass the test for the amount of emissions, and an increased pressure is created in its fuel tank.
Currently, modern cars are equipped with numerous systems that work together to reduce substances that reduce the quality of atmospheric air and create smog emissions. One of the first lines of defense for potentially dangerous gases and particles is the fuel vapor control canister solenoid valve, or simply the EVAP valve.
The adsorber valve is a component of a system designed to collect and recycle fuel fumes treated with an EVAP filter. The filter contains a carbon adsorbent that collects unburned hydrocarbons formed in the fuel tank. These vapors enter the filter canister and are processed into two different gases. Gasoline vapors, during a process called an adsorber purge, flow from the filter when the valve is opened into the fuel system and burn there during fuel combustion. Purified vapors are converted to carbon dioxide and vented to the atmosphere using the same EVAP valve.
The valve is usually open when the car is running and closed when the engine is off. The operation of the adsorber valve consists in passing air into the filter canister, where it is compressed by the evaporating fuel entering there. When the canister valve is working, air enters the EVAP system and releases the generated pressure to the atmosphere. This is how the system works on most American and domestic cars. With proper valve operation, it may be in good condition throughout the life of the vehicle. However, there are many reasons as a result of which the valve may wear out prematurely or become completely unusable.
When the valve fails, the OBD-II error code (0499) is usually turned on, indicating that there is a problem with the pressure in the EVAP system. A faulty valve does not allow fresh air into the EVAP system, which in itself can adversely affect the operation of the system. At the same time, the “check engine” light may come on, and the car may not even start, especially in some severe cases. A faulty adsorber valve must be replaced.
* Note. An EVAP canister solenoid valve is usually located near the fuel tank. In most cases, a valve is replaced to eliminate the problem. However, in some cases, the canister valve is attached to the vent tube, which is recommended to be replaced at the same time as the valve itself. For more precise instructions on the location of the valve and its replacement, please refer to the instruction manual.
* Since we started informing you about the valve replacement steps, I would like to clarify that its exact location depends on the design features of your car.
Part 1 of 3: Identifying the Signs of a Faulty EVAP Canister Valve
Before you decide to replace any mechanical component, it is very important to determine whether you diagnosed the problem correctly. When the first signs of a malfunction of the adsorber valve, as a rule, symptoms begin to appear, which will inform the driver about the occurrence of the problem. However, due to the fact that these symptoms may be attributed to other components of this system, a visual check or scan will be required to determine the defective part.
Some alarming signs of an EVAP canister valve problem that need to be replaced include the following:
- The “check engine” light is still on. This light bulb is the first light indicator that detects a potential problem with an EVAP valve. The light comes on if the engine control unit detects problems with the EVAP canister valve position and signal strength, leakage, or electrical failure. If the light is still on, you need to scan and search for the OBD-II error code code # 0499.
- Tank pressure too high. A typical sign of a faulty EVAP valve is an overpressure in the fuel tank. This is easily noticed when opening the tank. If, when the cover is removed or loosened, air is released under pressure, this indicates a malfunction. It may also be caused by high temperature, the pressure may rise naturally due to hot weather. The EVAP canister valve helps reduce this pressure in many cases.
- The fuel tank seems full when refueling. With excessive pressure inside the tank, refueling a car with gasoline can be difficult. Usually during refueling, you push the handle on the refueling gun and set it to the depressed position to refuel the tank. If after this a frequent shutdown of the pump occurs, as when filling the tank, this indicates excessive pressure inside the tank. This may be due to a failure of the evaporative evaporative solenoid valve.
- The fuel tank seems full when refueling. It can be difficult. In case of refueling, refueling position to refuel the tank. If this is the case, the pump will not be contaminated. This may be due to the evaporative evaporative solenoid valve.
Part 2 of 3: Replacing the EVAP Solenoid Adsorber Valve
Do not forget to wear goggles at all stages of this project, since the risk of small particles getting into the eyes is very high when working under the vehicle.
- Disconnect the battery. The EVAP canister solenoid valve is connected to the vehicle’s power source to switch its position from on to off. Therefore, the first thing to do before starting valve replacement is to disconnect the power source. Locate the battery and disconnect the positive and negative cables before proceeding.
- Raise the back of the car. To access the adsorber valve you need, you will need to pick up the car. This part is located near the rear wheels on the driver’s side. Raise the back of the car on the jacks, setting them in the places recommended for this, and place the stand under the back of the car. For greater security when installing on a stand, leave some of the load on the jacks.
- Determine the location of the bolts and slots holding the adsorber valve. The valve is fastened with a single bolt (in some – two) and fixed in several slots. The valve is inserted into these grooves with its guides for support.
- Treat the bolts and grooves with penetrating fluid. Since this component is exposed to various factors, it is likely that the bolts and grooves holding this part are rusty. In order not to damage the bolts when loosening, apply a penetrating spray on all the valve holding parts.
- Remove the attached electrical wiring. An electrical wiring is attached to the canister valve. This wiring can be removed by inserting the blade of a small flat screwdriver into the slot to which a small plastic terminal is attached. Remove the terminal with a screwdriver and carefully disconnect the wiring cable from the valve.
- Disconnecting the hoses from the valve adsorber. Two hoses are attached to the EVAP valve. One of them goes to the EVAP filter, and the second goes to the exhaust line. Most often, these hoses are fixed with special clamps or simply thrown over to the place of connection. It will be necessary to remove both attached to the valve hose.
- Remove the adsorber valve retaining bolts. Usually we are talking about one or two bolts that secure this part to its place. Remove these bolts using a ratchet wrench, an extension and a 10 mm head (in most cases this should be a 10 mm wrench).
- Remove the canister valve from its mountings. In many cases, this part is attached with a few clips on its rear wall. You can access these latches after you remove the valve mounting bolts. Using a flat-blade screwdriver, carefully squeeze the latches and pull the valve out of its mounting.
- Remove the old EVAP canister valve. When you unscrew the mounting bolts and loosen all fasteners, this should be easy. In some cases, a secondary ground wire is attached to the valve. Then you just need to remove this grounding wire, and the part is easily released.
- Installing a new valve adsorber. When the old valve is dismantled, you can begin to install a new one. To perform this step, perform the above steps in the reverse order, namely: * Insert the valve into the retainers and fasten it to the fixing point with bolts. * Connect the hoses and electrical wiring loop.
- Do the cleaning under the car. Before you finish work, make sure that the bottom of the lifted car does not contain the forgotten tools, debris and accessories used in the repair. When installing the car on the ground, nothing should remain under its bottom.
- Lower the car from the stands to the ground.
- Connect the battery.
- Start the engine, use the scanner to check and remove the error code.
Part 3 of 3: check the car in motion
After you have successfully replaced the fuel vapor purge valve, you will need to check your vehicle in motion. Hopefully, you have well remembered the symptoms that led to the replacement of the component, because the goal of the upcoming test drive is to make sure that they disappear. In fact, after such a repair, a small trip is sufficient, since if the symptoms remain, they will appear already at the start of the engine or when it is at idle.
The following notes are tips for performing a test drive or for determining the correctness of the work done to replace a defective part.
- Start the car engine. Let it warm up to the required temperature.
- Check the gauges on the dashboard. Make sure the check engine light is no longer lit. If it is still lit, stop the engine and perform a diagnostic scan. The error code will disappear after performing this procedure on most vehicles.
- Stop the engine. After the test has shown that no warning lights are no longer lit, turn off the engine.
- Remove the fuel cap. This is done to check if a vacuum is created in the tank. If when removing the tank cover under it a large amount of vacuum is detected, then it is necessary to check the correctness of the hose connections. Perhaps they were mixed up in places.
- Perform a test trip, namely 15 km on the road. Upon returning home, make sure that the “check engine” light and other warning lights are off.
This job is fairly simple to perform, but since this affects the EVAP system and the fuel system, some difficulties may arise. If, after reading these instructions, you still do not feel confident to carry out such repairs, please contact a certified mechanic for replacing the canister solenoid valve and removing fuel vapors.