A hard starting, rough idling, and decreased fuel efficiency – these are just some of the telltale signs of a failing purge valve.
This essential component of your car’s emissions system plays a crucial role in engine performance, and when it malfunctions, it can lead to a range of frustrating problems. Let’s learn about the symptoms of a bad purge valve to get timely methods.
What Is a Purge Valve?
The purge valve, also known as a canister purge valve, is part of the evaporative emissions control (EVAP) system. It’s an electronically controlled solenoid and when the engine is off or the purge valve hasn’t been activated by the PCM, it’s closed and traps the vapors inside the charcoal canister.
With the engine running and at operating temperature, though, it pulses open and closed, regulating the flow of fuel vapors into the intake.
The purge valve solenoid is mounted in the engine bay at the intake, connected to a hose roughly the size of a vacuum line and an electrical connector. Often, you’ll find it mounted near the center of the engine bay at the firewall.
Because car designs vary, some models might be in a different location somewhere between the fuel tank and the intake.
What Does a Purge Valve Do?
That allows fuel vapors to move from the charcoal canister to the intake where they can be burned. The purposes are simple: to reduce harmful emissions and to improve fuel efficiency.
Fuel vapors are burned rather than released into the atmosphere where they contribute to pollution, and as an added benefit, the vapors are converted into power when they’re combusted – although this is a minimal amount.
Until the evap purge valve opens, the fuel vapors are stored in the charcoal canister where they may condense, then be funneled back to the fuel tank.
How Does A Purge Valve Work?
The purge valve is typically located between the fuel tank and the intake manifold and is connected to the EVAP system’s hoses and tubing. It is controlled by the engine’s powertrain control module (PCM) and typically opens at a specific temperature and RPM.
When the valve opens, the fuel vapors flow from the evaporative canister into the intake manifold. This process helps reduce harmful hydrocarbon emissions and improves fuel efficiency.
When the PCM sends a signal to open the valve, the valve allows the fuel vapors to flow into the engine. When the valve is closed, the fuel vapors are trapped in the evaporative canister and held until the next time the valve opens.
Some purge valves also have a pressure sensor to detect when the EVAP system leaks. When this happens, the PCM will signal the check engine light to come on, indicating that the system is not functioning correctly and needs to be checked by a technician.
Location
Within most applications, the vapor canister purge valve is located within a vehicle’s engine bay, often within close proximity to the engine’s intake manifold. In some cases, the purge valve can be found mounted directly to the intake or plenum itself.
If you ever find yourself in question as to where your vehicle’s EVAP purge valve is mounted, you can actually trace the common fuel lines between the EVAP canister and purge valve by hand. These lines, at their end opposite the EVAP canister, will meet the inlet of the purge valve or solenoid.
What are Bad Purge Valve Symptoms?
If you have a bad purge valve, the situation would be worse than a non-working charcoal canister.
Here are the symptoms that could help you decide that it is the purge valve that has been creating issues:
The check engine light turns “ON”
While there are a dozen reasons that can lead to the illumination of the check engine light, a bad purge valve could be one of them. There are sensors present in the car’s system that track the working of the purge valve, and once the signals from the valve fail to transmit; an indication is a result.
Once the sensors detect a loss of signal from the valve, the information gets further communicated to the engine control unit. This is why the dashboard light illuminates indicating that you have been driving with a bad purge valve.
Rough idling
Is being stuck in a traffic jam with the engine “ON” a common thing to you? If yes, you would know how smoothly or roughly your vehicle handles it. In case you have been noticing a change that has resulted in rough idling, you need to visit a mechanic.
The chances are that the purge valve has been failing and requires your attention. Do not overlook the issue as it could lead to halting of the engine altogether as vacuum leaks are too likely to occur.
Tricky ignition
When your car is dealing with a vacuum leak, it is likely that you will find it challenging to start the car. This problem is even more consistent when it is the purge valve that has gone haywire.
The vacuum leak would further create a let-in through which air enters the engine and interrupts the combustion process big time. Now, that is not much of a favorable situation! You could also refer to maintenance tips for more problems that could lead to delays in starting your vehicle.
Engine performance is not up to the mark
If you are a lover of high speeds, a poor purge valve will ruin the entire fun of driving. The engine performance would get poor, and no matter how hard you try, the power generation would deteriorate.
In case you have already started missing your smooth rides, you need to visit a mechanic. You need to take care of such small issues when moving with the desired speeds in your mind.
The emission test failures
Do you know that a purge valve prevents toxic hydrocarbons from being ejaculated from the tailpipe? Then, when you have a bad purge valve, the toxic hydrocarbons would exit the internal system.
Such a situation would not be good for your emission control tests. With more toxicity in the air, you would also be reducing your carbon footprint. If it is the purge valve that has been creating the mess, you’d better get it repaired or replaced as need be.
Poor fuel efficiency
If the purge valve is stuck open, it can cause excess fuel vapor to be drawn into the engine, which can lead to poor fuel efficiency.
Hard starting
A malfunctioning purge valve can cause hard starting or starting issues. This is because excess fuel vapor in the engine can cause flooding, making it difficult to start the engine.
If you experience any of these symptoms, it’s essential to have your vehicle inspected by a qualified mechanic. They can diagnose the problem accurately and determine if the purge valve needs to be replaced.
How To Test A Faulty Purge Valve
- Visual Inspection: The first step is to locate the purge valve. It’s typically found near the engine intake manifold. Look for any obvious signs of damage or leakage.
- Check Engine Light: If your check engine light is on, use an OBD-II scanner to read the error codes in your vehicle’s computer. Codes related to the EVAP system such as P0443, P0444 or P0445 can indicate a problem with the purge valve.
- Bench Testing: Remove the purge valve from the vehicle for a bench test. Apply voltage to the purge valve’s electrical connector (typically 12V). You should hear a click when the valve opens. If not, the valve is likely faulty and needs to be replaced.
- Vacuum Test: Another way to test the purge valve is by using a vacuum pump. With the purge valve removed from the vehicle, apply vacuum to the valve and see if it holds. If vacuum drops, the valve is leaking and needs to be replaced.
- Professional Diagnosis: If you are unable to perform these tests yourself, consider taking your vehicle to a professional mechanic. They have specialized tools and expertise to accurately diagnose a faulty purge valve.
How Much Does It Cost To Replace A Malfunctioning Purge Valve?
The cost of replacing a malfunctioning purge valve can vary depending on the make and model of your vehicle, your location, and whether you choose to do the work yourself or hire a professional. On average, you can expect to pay between $100 and $200 for a new purge valve part.
If you choose to hire a professional mechanic to replace the purge valve, the cost will typically be higher due to the additional labor costs. The total cost, including both parts and labor, can range from $150 to $300 or more.
Keep in mind these are just average estimates, and the actual cost can vary. It’s always a good idea to get a few quotes from different mechanics or auto repair shops to ensure you’re getting a fair price.
Is It Safe to Continue Driving?
While it is possible to continue driving a vehicle with a faulty vapor canister purge valve, doing so for extended periods of time is not advised. Attempting to drive a vehicle in this condition can present numerous operability and emissions-related concerns.
In some cases, the failure of the EVAP purge valve can actually produce a “lean” condition within an engine, thereby causing potential misfires and reduced combustion efficiency.
It is also important to note that a vehicle is unlikely to achieve passing emissions testing results in the event that its EVAP purge valve has failed, in states where this testing is mandated. In turn, it can lead to problems attempting to register a vehicle, or when attempting to renew this registration.
In any case, you should attempt to resolve the root cause of your vehicle’s EVAP emissions system issues as soon as possible, even if EVAP purge valve replacement proves necessary. Doing so will help make sure that your vehicle continues running at peak efficiency, and complies with all applicable emissions standards.