5 Symptoms of a Bad Vapor Canister Purge Valve (and Replacement Cost)
Gasoline contains over 150 toxic chemicals. Inhaling fumes can cause dizziness, headaches, and breathing issues and long-term exposure may be fatal. Because of that, federal laws require technology like the purge valve solenoid to reduce these harmful vapors.
If the solenoid fails, vapor and emissions release unchecked. Keep reading to learn the early signs of a faulty vapor canister purge valve as well as how much replacement is going to cost.
What Is a Vapor Canister Purge Valve?
A vapor canister purge valve is a component within a vehicle’s evaporative emissions system. This system itself is engineered to minimize the amount of gasoline vapor dissipated into the environment, in a bid to meet emissions standards of the current era.
Alternatively, the vapor canister purge valve is also often referred to as an EVAP purge valve or charcoal canister purge solenoid. By any name, the device’s functions are virtually identical across all vehicles, serving as a gatekeeper of sorts, when it comes to managing the flow and redirection of gasoline vapors.
Purpose
The vapor canister purge valve is an electrically controlled device that responds to ECM/PCM directed commands, allowing the redirection of gasoline vapor to a vehicle’s engine for further combustion. Once de-energized, this valve returns to a closed position, resulting in the retention of fuel vapors by the EVAP canister itself.
It is worth noting that most early EVAP purge valves were actually vacuum-actuated, rather than electrically-driven as they are today.
Modern EVAP purge valves are typically gated to the “open” position during engine operation. The opening of this valve occurs when a vehicle’s engine is started, assuming no EVAP leak self-checks are being performed by the vehicle’s ECM/PCM.
The purge valve is then closed once more, whenever ignition power is withdrawn.
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.
Bad Vapor Canister Purge Valve Symptoms
Vapor canister purge valve failure is often associated with a number of underlying symptoms, some of which can prove rather troubling to contend with. The following are several of the most common of these symptoms.
#1 – Illuminated Check Engine Light
In almost every case, a failed or faulty EVAP purge valve will lead to the illumination of a vehicle’s check engine light.
Because the normal flow of fuel vapors is disrupted, this light is illuminated upon the logging of one or more corresponding EVAP system DTCs, such as P0441 or P0442.
#2 – Rough Idle/Reduced Performance
In the event of EVAP purge valve failure, you might notice that your vehicle’s performance is notably lacking. Performance reductions of this nature are most prominent at lower RPM, though issues under heavier load are not unheard of. A rough or erratic idle is also commonly observed.
#3 – Hard-Start/No-Start Condition
Yet another potential sign of EVAP purge valve failure is the inability to start a vehicle, despite strong cranking, or reluctant starting under the same circumstances. Depending upon the position in which the purge valve itself is seized, this tends to stem from a rich/lean fueling condition.
If the valve is stuck open, it may allow too much fuel vapor into the engine, creating an overly rich mixture that’s difficult to ignite. Conversely, if the valve is stuck closed, it can lead to a lean condition, where there’s not enough fuel for proper combustion.
Both scenarios can result in frustrating start-up issues, even when the battery and starter motor are functioning correctly.
#4 – Reduced Fuel Economy
A stuck or seized control valve can lead to a noticeable reduction in fuel economy. This stems from skewed air-to-fuel ratios that stem from unpredictable vapor distribution, which differ significantly from that which is anticipated by a vehicle’s ECM/PCM.
This fuel to air imbalance forces the engine to work harder and less efficiently, consuming more fuel than necessary to produce the same power output. As a result, you may find yourself visiting the gas station more frequently.
#5 – Failed Emissions Test
The vapor canister purge valve is a critical component of a vehicle’s EVAP system. Its failure will often result in non-compliance during subsequent emissions tests. If your vehicle has recently failed such testing, the vapor canister purge valve could be to blame.
If the valve is malfunctioning, it prevents the proper recycling of fuel vapors, allowing them to escape into the atmosphere instead of being reintroduced into the engine for combustion. This increase in hydrocarbon emissions will most likely cause your vehicle to exceed the allowable limits set by emissions testing facilities.
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.
Vapor Canister Purge Valve Replacement Cost
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The cost associated with replacing a defective vapor canister purge valve often varies from one model and year of vehicle to the next, due to natural fluctuations in parts pricing and billable labor.
But generally speaking, you can expect to pay between $200-$450 to have your vehicle’s damaged or defective vapor canister purge valve replaced.
More often than not, the most significant portion of this cost can be attributed to the purchase of replacement components for installation. The actually labor component is fairly straightforward and can be completed in a DIY fashion if you have some basic mechanical skills.
Here’s a good video showing the replacement process on a 2007-2012 Chevy Suburban 1500.
What Causes the Valve to Fail?
There are several factors that are known to have an effect on the overall longevity of a vehicle’s vapor canister purge valve.
One common factor relates to the contamination of the purge valve itself with granular deposits. Over time, carbon and other particulate matter can find their way into the purge valve, thereby impeding operation.
Liquid contamination of the EVAP purge valve can also cause premature failure. This often occurs when a driver repeatedly overfills their fuel tank, attempting to “top it off”. Purge valves are meant to circulate vapor only, without the introduction of fluid. Therefore, with time, this type of contamination can cause premature degradation.
Diagnosing a Faulty Purge Valve
There are several key steps to follow when attempting to diagnose a faulty or failing vapor canister control valve. When due consideration is given to each of these steps, a diagnosis is often achieved in a timely manner.
#1 – Check Additional DTCs
Before beginning the diagnostic process, check for the presence of additional DTCs via a good scan tool (here are our recommendations). Thoroughly diagnose any additional faults that are evident so you’re not trying to fix multiple unrelated issues at the same time.
#2 – Inspect EVAP Valve/Wiring
Begin by carefully inspecting the engine’s EVAP purge valve for signs of damage. Any damage that is evident must be repaired before proceeding.
#3 – Check Resistance
With the use of a quality multimeter, check for resistance across the positive/negative pins of the EVAP purge valve. These readings should be compared to those specified by the vehicle’s manufacturer. Readings outside of this range will necessitate replacement.
#4 – Troubleshoot Electrical Faults
If prior resistance testing does not indicate an issue with the EVAP purge valve itself, further troubleshooting of power/ground feed to the purge valve will be required. At this point, professional help is generally recommended for most.
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Fixed purge valve check engine came back on p4402
Sounds like there is a leak in the evap system. They make kits that can help you detect evap leaks yourself, if that is something you are interested in.
Where to get the kit and how does it work ?
You can find them online. Just search something like “evap leak kit” or “automotive smoke tester” and see what comes up.
Basically the kit pumps smoke into the system, allowing you to clearly see any leaks in vacuum or evap lines. If you have a leak, the smoke will come out of some place where it’s not supposed to.