Emissions system

Purge valve was replaced last week and engine light came back on 4 days later. Mechanics at shop say now I need a new gas cap. Is This coincidental that both stopped working at same time? It feels like I paid $170 last week was for nothing especially if it's just needed a gas cap. Thoughts please and recommendations

My car has 64000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
This is not coincidental as the purge valve and the gas cap, among other parts work together to keep your fuel evaporative emissions system in check. The EVAP system prevents fuel vapors from the fuel tank from escaping into the atmosphere. The EVAP system collects and temporarily stores the fuel vapors in the charcoal canister. The charcoal canister is filled with activated carbon pellets that can absorb the fuel vapors. When the engine is running, the fuel vapors are purged from the canister and burned in the engine.

The vent control valve (solenoid) controls the flow of outside air in and out of the charcoal canister. One side of the vent valve is connected to the charcoal canister. The other side is connected to the vent hose that has a filter or screen at the end and is attached to the car body or frame. In some cars, the vent valve is attached to the canister. In others, it’s installed separately near the canister. The vent valve is controlled by the engine computer (PCM). Normally the vent valve is open. It closes when the engine computer tests the EVAP system for leaks. If a leak in the EVAP system is detected, the Check Engine light will illuminate on the dash and the trouble code related to the problem will be stored in the engine computer.

When an air leak is present in the EVAP system, the MAP sensor will not be able to determine the air density, and the MAF sensor will not be able to determine the volume of air, entering the engine correctly. This will lead to an over fueling situation or an under fueling situation depending on the size of the air leak and engine operating speeds and load. This may eventually lead to catalytic converter problems as well as misfiring problems. I would recommend having an expert from Your Mechanic come to your home to take a look at your car to diagnose your EVAP purge solenoid.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

What Does Volkswagen Passat Code P0456 Mean? Volkswagen Passat P0456 definition: Evaporative emission control system leak (small). Repair Urgency: Get this fixed within the next month to prevent drivability problems and excessive fuel consumption.
A failure to maintain the correct fuel tank pressure results in trouble code P0456. This means that a leak is allowing vapors to escape, either directly from the fuel tank or from related hoses and parts.
The most common causes for EVAP leaks include bad seals and O-rings, a failing purge valve, a damaged hose or vent, or a defective leak detection pump. As you might have guessed, there`s no real way to prevent one of those components from failing unless you`d like to regularly replace components of your fuel system.
Yes, you are still safe to drive. The EVAP (Evaporated Emission Control System) is used to prevent gasoline vapors from escaping into the air from the fuel tank system to control greenhouse emissions.
When you don`t fix an EVAP problem, the check engine light will stay on, masking other problems that might occur. Of course, if local regulations require passing an emissions test, your vehicle will fail. Finally, harmful emissions are being released into the atmosphere.
An EVAP leak can cause a variety of issues, including a decrease in fuel efficiency, an increase in emissions, and a decrease in engine performance. If left unchecked, an EVAP leak can also cause damage to the catalytic converter, which can be expensive to repair.
What Does Volkswagen Jetta Code P0456 Mean? Volkswagen Jetta P0456 definition: Evaporative emission control system leak (small). Repair Urgency: Get this fixed within the next month to prevent drivability problems and excessive fuel consumption.
It`s just like a regular trouble code, except it can`t be cleared with a scanner, or by disconnecting the battery. A permanent code is stored in non-volatile memory and the only way to erase it is for the car to run the same test that caused the code to set in the first place, but, of course, it needs to pass the test.
P0456 means a small leak in your evaporative system. This is often a super simple fix (hint: it`s your gas cap), we do offer some more complex issue breakdowns. The evaporative emission control (EVAP) system prevents fuel vapors from escaping into the atmosphere.
The EVAP system leak error means the sensor detected the Evaporated fuel in the gas tank is leaking. If this fault is detected multiple times, it is recommended to have the vehicle serviced by a mechanic to resolve the leak.
The national cost for a fuel evaporative canister replacement in 2023 is between $80 and $581 with an average of $183.
Smoke Test – The idea behind the smoke test is simple, blow smoke into the EVAP system and look for smoke escaping from a compromised valve, seal, tube, or hose. Smoke testing is the best way to test the EVAP system. At the same time, it`s also either the most expensive or bravest method of doing to.
On top of a rough idle, a vehicle with a failing EVAP canister purge valve will display signs of poor engine performance. The engine may feel like its running “weak” and won`t generate sufficient power for acceleration. Accelerating will feel like you`re pressing the pedal down and moving slower.
Can I Still Drive with a P0496 Code? It`s important to seek repairs from a mechanic as soon as possible to avoid further, more serious damage to your vehicle that will result in your car not starting at all. It makes sense to be proactive whenever the check engine light stays on.
You can eliminate the canister and associated hardware, but you`ll still need the vent line. To make it roll over proof, the vent line should be routed UP from the tank, probably about 1-2 feet, then routed down to below the tank bottom (by a foot or more if possible).
The P0455 diagnostic trouble code appears when there`s a leak in the Evaporative Emission Control (EVAP) system, and the system can`t maintain pressure. The EVAP system usually consists of five main components: the fuel tank, fuel cap, vent valve, purge valve, and the evaporative canister (or charcoal canister).
An evap leak is the same thing as a vacuum leak. A vacuum leak will certainly cause the engine to run roughly. I would recommend having your vacuum levels checked with a vacuum gauge by a qualified professional to determine whether they are in specification.
P0456 means a small leak in your evaporative system. This is often a super simple fix (hint: it`s your gas cap), we do offer some more complex issue breakdowns. The evaporative emission control (EVAP) system prevents fuel vapors from escaping into the atmosphere.
The P0456 generic fault code is considered low on the severity scale, so driving your car is safe, but you`ll need to address the issue as soon as possible to avoid decreased fuel economy and increased emissions.
P0456 is an evaporative emissions system code. That`s the system that checks to make sure your fuel tank isn`t spewing fuel vapor into the atmosphere. For this Honda fit, P0456 indicates there is a “very small leak” in the system.
The P0456 generic fault code is considered low on the severity scale, so driving your car is safe, but you`ll need to address the issue as soon as possible to avoid decreased fuel economy and increased emissions.
P0456 is an evaporative emissions system code. That`s the system that checks to make sure your fuel tank isn`t spewing fuel vapor into the atmosphere. For this Honda fit, P0456 indicates there is a “very small leak” in the system.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

My car doesn’t pass emissions because the catalyst system is below threshold, and the exhaust gas recirculalation is insufficient.
ANSWER : Hi there. The Engine Gas Recirculation (EGR) valve could be sticking or full of deposits from the exhaust system. Remove and clean the EGR valve before replacing it to see if the system will begin to operate. The oxygen sensors that measure the catalytic converter is picking up an uneven measure. This says that the catalytic converter is below threshold, but if the system is too lean, the same code will come up. Simply fixing the EGR valve will fix the emissions and should make the engine light go out. I recommend driving the vehicle for a week after the light goes out before heading to the emission station.

Billing question sent to CS for the cost of fixing the vehicle to pass emissions.

Read Full Q/A … : Emissions system

Evaporative Emission Control System Purge Control Valve Circuit Malfunction how to fix and where is it ?
ANSWER : Hi there. The best advice I can offer is for you to complete one of two things. First, it would probably be best to have a professional mobile mechanic come to your location and complete a check engine light inspection so they can pinpoint what part of the EVAP system is causing your failed emissions test. If you decide you want to do this on your own, then it would be a good idea to purchase a service and repair manual for your Ford Mustang – so you can look at detailed diagrams and replacement instructions.

Read Full Q/A … : Emissions system

check emission system and burning smell 2010 Acura TSX
ANSWER : Hello – you have multiple, unrelated problems here. The Vehicle Stability Assist (VSA) system may only have a problem with a wheel speed sensor, a common problem with electronic stability and anti-skid brake systems. The emissions and "burning smell" problem will require a more extensive check of engine codes and possible failures like a stuck exhaust gas recirculation valve. I would recommend a engine inspection by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.

Read Full Q/A … : Emissions system

How can you tell if you need a canister replacement or a whole new emissions control system?
ANSWER : The emission control system faults can produce many different codes and the code is used to do different pinpoint tests on the system to find the cause for the code and check engine light coming on. There may be a simple gas cap loose or one of the many components leaking in the system and needs further testing. There is no code to replace the entire emission system.

Read Full Q/A … : Emissions system

check break system and indicators of side brake, doors open,and traction system and full light warning in dash board
ANSWER : Hi there, thanks for writing in.

It sounds like you are having a serious electrical malfunction, which is very hard to diagnose without being able to look at the car first hand. The first step to diagnosing your electrical issue would be to scan all the relevant control modules in the vehicle, to see if there are any faults relating to any of these issues. It sounds like somebody at the dealer has been trying to fix this problem, so it may be a more involved one. I have personally seen failed control modules cause things like this, but that is no guarantee that it’s the problem in your case. It would be best to have a qualified independent technician, such as one from YourMechanic, look at your car to diagnose your electrical problem.

Read Full Q/A … : Emissions system

Service ABS System, Traction Control System and Service Stability System
ANSWER : Hello. These systems are interconnected, since both of them can control individual wheel brake functions when operating. It is likely that one of the speed sensors are failing. To have this verified, have a qualified professional, like one from YourMechanic, diagnose the warning lights, pinpoint the fault(s), and make necessary repairs.

Read Full Q/A … : Emissions system

Intermittent random faults showing up on dash and I drive system. One at a time. Mainly transmission error and lighting system err
ANSWER : Hello. When it comes to power issues while driving, it is typically related to the charging system in some way. A miscommunication with the battery would effect the performance. Before getting too technical, start with the simple stuff. Check the alternator output with a voltmeter, or have it tested at your local automotive store. If both the battery and the alternator are in good working condition, then you can turn your attention to a control module or a programming issue. The warning codes that are being triggered should be read and used to help in the diagnosis. If several different systems are failing, you will likely have a charging system error, or a malfunctioning control module. Further testing is needed.

Read Full Q/A … : Emissions system

What is the evaporative emissions control system?
ANSWER : Gasoline evaporates, even in the gas tank of your Accord. If those fumes are allowed to escape into the atmosphere, they create hydrocarbons that damage the environment and also contribute to smog/air pollution. To help combat this problem, your car uses an evaporative emissions control system. Basically, there’s a charcoal canister in the fuel system that absorbs fuel vapor. If you’re not driving, it just stores the vapors. Once you start driving, the vapors are sent to the engine where they’re burned (also increasing fuel mileage).

Read Full Q/A … : Emissions system