P0446 Chevy – What Is It, And How To Fix It?

by Conner Mckay

P0446 Chevy is a problem code that necessitates further investigation. Mechanics and car owners seek more information about this EVAP-related issue code. You’ll find all the information you need about the P0446 error code right here.

A mechanic’s most crucial equipment is undoubtedly an OBD II scanner. It not only allows for the quick detection of hidden flaws in a car, but it also saves you a lot of time and money compared to traditional diagnostic methods.

Trouble codes appear, each with its own set of advantages and downsides. At one end, they indicate problems that are difficult to diagnose. On the other hand, they can be a sign of a major failure. Let’s look at what P0446 Toyota, P0446 Chevy Silverado, and P0446 Ford mean, how to fix it, and what causes it. On top of that, we’ll talk about the prices of the repair. Let’s get started.


P0446 Chevy, also known as evaporative emission system vent control circuit malfunction, indicates that the computer in your vehicle has discovered (or believes it has identified) a problem with the operation of the EVAP system vent valve.

The vent valve is managed by your car’s computer (it also controls the purge valve). Furthermore, the computer monitors the valve and its control circuit for any abnormalities. P0446 indicates that an electrical failure has been identified in either the or its control circuit.

While the P0446 Chevy code can signal an electrical problem on later model Fords, which for some unexplained reason decides to look at the vent valve or EVAP solenoid electrical circuit to set this code, the P0446 code is highly unlikely to constitute an electrical worry on other manufacturers.

When the canister would not vent after the EVAP test, GMs and older Fords would set this code, and in those circumstances, mechanical clogging was considerably more likely to be the cause.

It’s worth noting that code P0446 is more common on older automobiles, especially those made by domestic manufacturers such as GM.

Evaporative Emission System Vent Control Circuit

One of your engine’s strategies to control dangerous emissions is the evaporative emission system vent control circuit. It stops fuel vapors from escaping into the atmosphere from the fuel tank.

These fumes are contained in the charcoal canister and absorbed by small activated charcoal pellets. Two primary valves control the flow of air into and out of the system:

  • The vent control valve is an electrical valve that regulates the air supply into the charcoal canister and is controlled by the engine control module (ECM). It’s commonly mounted near or on the charcoal canister in the back of the car.
  • Vapors from the EVAP system can pass through the engine air intake and be burned due to the purge volume control valve.

When the engine is turned on, the vent control valve is normally open, while the purge volume control valve is normally closed. When the ECM is ready to release the fuel vapors, it releases the purge valve, which causes the stored vapors in the charcoal canister to be burned.

The ECM runs periodic leak tests when the vehicle is shut off to ensure that the EVAP emission control system is working properly. During these tests, the ECM turns off the EVAP system by closing both the vent and purge control valves, resulting in a sealed EVAP system. The ECM then checks the pressure of the EVAP system.

If the EVAP system fails to keep the right pressure during the leak test, or if the ECM detects a fault in the vent control valve activation circuit, the P0446 code can be seen.

Here is a link to a Silverado EVAP system diagram that will help you understand it better.

EVAP Canister Vent Solenoid

The EVAP system is essentially a set of components that work together to keep fuel vapors from entering the atmosphere. The gas tank, the gas cap, the vent valve, the purge valve, and the charcoal canister are the major components of an EVAP system, though system designs vary.

Fuel vapors are retained in the charcoal canister rather than leaking into the atmosphere when the engine is turned off. The purge valve opens once the engine is running. All of the necessary conditions are satisfied, allowing the vapors to enter the engine and be consumed during the usual combustion process.

The vent valve that allows fresh air to enter the charcoal canister is normally open. However, when the computer in your car needs to check for leaks in the EVAP system, it tells the electrically controlled vent valve to close, effectively sealing everything off. After that, the system can perform a self-test.

Because the vent valve is normally open, a P0446 will not be generated on most platforms unless there is an electrical fault. In some circumstances, the vent valve will remain mechanically open, venting the canister continuously and resulting in a different code, such as a P0455.

It’s more likely that there’s a clog in the vent or a mechanically jammed closed vent valve. However, the year, manufacture, and model of the car would all play a role.

P0446 Chevy Symptoms

When the EVAP canister vent solenoid fails, fresh air cannot enter the EVAP system, which can have a detrimental impact on the system’s performance. A faulty or malfunctioning EVAP canister vent solenoid usually causes a few symptoms that alert the driver to a potential problem that has to be addressed.

P0446 Chevy

1. The Check Engine Light Is Illuminated

An illuminated check engine light is one of the earliest signs of an EVAP canister vent solenoid malfunction. The check engine light may illuminate if the computer identifies a problem with the EVAP vent solenoid signal, location, or circuit.

2. Gas Tank Pressure

Another indicator of a problem with the EVAP canister vent solenoid is pressure in the fuel tank.

If the EVAP vent solenoid fails, the pressure in the vehicle’s fuel tank may not be able to be adequately vented and released. When the fuel tank is opened, this can cause increased pressure to build up and then release.

3. Emissions Test Failure

Another indicator of a possible problem with the EVAP canister vent solenoid is a failed emissions test. If the EVAP vent solenoid fails or develops any vacuum leaks, the entire system will be hampered. This could lead to a failed emissions test, which must be fixed before the automobile can be lawfully driven on the road.

The EVAP canister vent solenoid is a critical component, and any difficulties with it can result in emissions issues. Have your car evaluated by a competent mechanic if you feel your EVAP vent solenoid is malfunctioning. They will be able to diagnose any problems with your vehicle and, if necessary, replace the evaporation vent solenoid.

What Causes The Code P0446 Chevy?

As you may know, the P0446 code is activated by a leak in the EVAP system. Is it, however, that straightforward? The answer is a spectrum ranging from a firm yes to an affirmative no. The difficulty of the repair operation varies depending on what caused the P0446 to appear. It could be as simple as tightening the cap on your fuel tank.

It can also be as difficult and frustrating as a lengthy diagnosis procedure followed by several hours of repair time. Similarly, the cost of resolving the problem might range from nothing to hundreds of dollars, depending on what is creating the problem.

P0446 Chevy

It’s nearly tough to figure out what’s causing P0446 when it first appears. The check engine light is the first symptom you’ll notice. However, this might signify a variety of things. You’ll need to use an OBD II reader to get a more detailed diagnosis. If you get a P0446 error number, the next step is to figure out what’s causing it.

Let’s look at the most common causes of the P0446 code to learn more about it.

1. A Fuel Tank With A Loose Cap

This is the cheapest problem to solve out of all the issues that cause the P0446 code. A fuel tank cap may appear to be a simple component, but it covers a lot more. The gasoline tank cap is meant to keep the pressure inside the tank constant.

If there is a leak in this system, the sensors can become completely unbalanced. This code may appear as a result of a pressure drop. As a result, a dangling gasoline tank cover can be alarming. It’s clear that this is a simple fix. Remove the gasoline tank cap and replace it properly.

The engine check light should go away after some time if this was the issue. So there you have it, a free solution to the P0446 code problem. If the P0446 code appears by itself, without any other codes, it is most likely the gasoline tank cap.

But what happens if the fuel tank cap breaks? The material inside the cap might wear out over time, causing cracks. The cap will then be unable to retain the pressure, and the cycle will begin again. However, there is no free remedy for this. It should not be too expensive, as a new gasoline tank top should suffice.

2. Fuel Tank Leakage

Things are getting a little more pricey now. Fuel tanks are designed to last a long time. The gasoline tanks in most modern cars are made of tough plastic that should last a long period. However, this does not mean they are impervious to harm.

The gas tanks themselves may develop cracks and begin to leak. And unsurprisingly, this is sufficient to bring up the code in question. The most typical cause of these cracks is hitting the tank on a speed bump or other road obstruction.

3. Hose Leaking In An EVAP System

The charcoal canister of an EVAP system is normally situated near the gasoline tank. It can be found in the engine bay of various vehicles. It will be connected to the fuel tank through appropriate hoses regardless of where it is positioned. These hoses transport the gasoline vapors to the canister.

Any leaking in these hoses, as expected, can result in the P0446 error code. The hose is long and might be difficult to identify, especially in vehicles with the canister positioned in the engine area. However, the ends of the hose are the most likely spot for a leak to occur.

The connections between the gasoline tank and the canister are prone to cracking. This does not, however, indicate that the rest of the hose is unbreakable. The ends, on the other hand, should be checked first.

You must take measures if you notice a severe decline at the conclusion. You can cut off the worn-out end of the hose and replace it if the length of the hose allows it. If the damage is severe and your car is older, though, you should replace the hose.

4. Charcoal Canister Leakage

The charcoal canister may develop leaks despite the fact that it is a stationary item with no movement. A leak in the canister, such as hose and gasoline tank leakage, can set off the P0446 code.

If there’s a leakage here, the entire system’s pressure might be jeopardized. As a result, a code has been generated. If this happens, it’s critical to figure out where the leak came from. The canister must be replaced if necessary.

5. Vent Control Valve Failure

The vent control valve is a complicated electrical component that is critical in maintaining proper pressure within the EVAP system. If it fails, it’s understandable that the P0446 code, along with a slew of other codes, will appear.

A short circuit in the system can cause an electrical component, such as the vent control valve to fail. If this happens, replace the evaporative emissions purge control valve. But first, let’s make sure it’s the valve that’s causing the problem. Accurate diagnosis is critical in this case, as a replacement can be costly. You don’t want to waste money on a repair that isn’t necessary.

6. Failure Of A Pressure Sensor

The right pressure must be maintained throughout the whole EVAP system. P0446 or a variety of other codes can be triggered by a leak or a drop in pressure, depending on what causes it. But what happens if the pressure sensor malfunctions?

A faulty pressure sensor can produce a wide range of incorrect values. This causes the ECM to believe there is a leak in the system, resulting in the code being triggered. The only way to repair this problem is to replace the pressure sensor. However, just as with the vent control valve, you must ensure that the sensor is the source of the problem before investing in a new one.

How Do You Diagnose The P0446 Chevy Error Code?

P0446 Chevy

You’ll Need The Following Tools:

  • OBD2 scanner with advanced features
  • Multimeter (digital)
  • Smoke machine
  1. Check for further issue codes by scanning your vehicle. If you notice PO440 or PO441 code in addition to P0446, the problem is likely to be more serious. After you’ve resolved any additional codes, scan your vehicle once again.
  2. Examine your gas cap. If it’s loose, tighten it, and replace it if it’s fractured or damaged. Also, look for any leaks or other damage in the gasoline tank.
  3. Examine the hoses that surround the EVAP system for breakage or defects. Any that have become loose should be reconnected, and any that have become broken should be replaced.
  4. Using an OBD2 scan tool, double-check the tank pressure data to ensure it’s accurate.
  5. Look for any leaks or other damage on the charcoal canister.
  6. Check all of the EVAP system’s valves and solenoids with the scan tool.
  7. The vent control valve and the purge valve should both be tested. To make sure they’re getting electricity, use a multimeter. Check the wiring if they aren’t.
  8. To check for leaks in the EVAP system, use a smoke machine. Close the vent solenoid with your scan tool or a multimeter while turning off the engine. Connect the smoke machine’s hose to the EVAP system and turn the unit on. Keep an eye on the indicator ball. If it rises over the red flag, the system is leaking.
  9. Use the “visible vapor” or “smoke” option on the smoke machine. Remove the fuel cap until smoke begins to emerge from the filler neck. Because the vapor in smoke machines is UV reactive, flashing a black light on your engine will help you find leaks more rapidly.

P0446 Chevy Repair Cost

As previously stated, the cost of repairing a P0446 code might range from nothing to a lot, depending on what went wrong. Sometimes simply tightening the fuel filler cap will suffice. There are occasions when more, a lot more, is required. It can take hours to figure out what’s causing the problem.

As a result, the diagnosis is a significant contributor to this expense, as identifying the actual problem can be difficult. It costs between $75 and $150. They will be able to provide you with an accurate price for the repair job only after completing this diagnosis.

With so much effort and money spent on diagnosing the P0446 code, it’s logical to do it yourself. You can save money by pointing out exactly what is wrong with your vehicle to the mechanic. As a result, the cost of repairing a P0446 is the sum of the components cost and the labor cost of the specific job.

Steps To Resolve The Error Code P0446 Chevy?

  1. During your diagnostic testing, any leaky or broken components will be replaced.
  2. The valves themselves are the most likely culprit if the vent control valve or purge valve receives electricity but does not open and close properly. Replace the clogged valve.
  3. The charcoal canister should be removed. You may clean it using compressed air. Start the air compressor on a flat surface and let the pressure develop to 50 psi before turning it off.
  4. Cover the other two apertures with your fingers and insert the nozzle into the vent control valve pipe on top of the canister. Allow 1-2 minutes for pressurized air to fill the canister.
  5. Test the EVAP system after replacing the charcoal canister. The charcoal canister may need to be replaced if it’s still failing.

P0446 Avoidance Tips

The easiest approach to avoid difficulties with your EVAP system is to do preventative maintenance on it on a regular basis. To begin, make sure your gas cap is securely fastened after each fill-up. Corrosion is the most prevalent source of system leaks. Thus rust prevention solutions in your system can help avoid it.

Is This A Severe Situation?

As previously said, you can drive normally even if this code is present. If a fuel leak causes the problem, you must address it as quickly as possible. While the vehicle will not be irreparably damaged, it will reduce your fuel consumption and efficiency.

Also, fixing any problem that triggers a check engine light is usually a smart idea. If not, it’ll be impossible to know when another component fails because the same light can indicate a variety of issues.

P0446 Code and Facts You Need to Know

  1. A P0446 error code indicates an evaporative emission control system (EVAP) vent control circuit malfunction, which could result in other codes appearing.
  2. The EVAP system is composed of several components, such as the gas tank, gas cap, charcoal canister, purge valve, and vent valve, that work to eliminate the chances of fuel vapors entering the air.
  3. The most common symptom of a P0446 error code is the illumination of your vehicle’s check engine light or the illumination of your malfunction indicator lamp.
  4. Causes for the display of a P0446 error code may vary, but the most common causes are a malfunctioning or clogged vent control valve or issues with the control circuit, such as faulty wiring.
  5. Overlooking a problem with your vehicle’s EVAP system could result in other integral vehicle components becoming damaged and other similar codes appearing. Seeking a qualified mechanic for repairs and diagnosis is best practice.
  6. A vehicle may still be operational with an EVAP leak (like a BMW P0442 problem), but it is best to stop to make sure the gas cap is still secure and take the car to a mechanic to ensure the leak is fixed.
  7. If you don’t have a lot of experience with complex auto repairs, it is best to have a professional technician check your car for error code P0446.
  8. Diagnosing a P0446 code must be accurate before all necessary repairs can be made, and an advanced scanning tool can help identify where the leak originated.
  9. Inspecting a P0446 code requires professional help, such as scanning the vehicle, checking the gas cap, performing an EVAP system leak check, and checking the EVAP vent control valve to ensure it works correctly.
  10. More extensive diagnostic tests might still be needed if the P0446 code persists, even after initial inspections and repairs.


What Is Code P0446 Chevy

This general OBD II code might detect an ineffective evaporative emission system vent control circuit. A malfunctioning evaporative emission system vent control circuit could prevent the pump from evaporating.

How To Fix P0446 Chevy

Gas caps are routinely used to repair code P0446, and they can be extremely cost-effective. Pinch the EVAP Vent Control Valve off in this situation. If the gasoline cap didn’t stop the leak, be sure they can get a hold of it before moving on to the next step. You can verify the smoke flow of the EVAP system with an EVAP leak checker.

Is P0446 Chevy Caused By A Purge Valve

P0446 could also be caused by a problem with the fuel tank pressure sensor in select GM vehicles. When an open purge valve on a Mazda Tribute or Mazda 6 becomes stuck, EVAP codes P0446 or other codes may appear. For a little fee, you can replace your purge solenoid.

Is It Safe To Drive With A P0446 Code

There is no immediate threat despite the code P0446. If you have this code, you may be able to drive your car. Other than when the check engine light comes on, you may notice poor fuel economy readings as a result. Although there is no guarantee that this code will cause any life-threatening problems, any indication that something could trigger a check engine light should be looked into.

What Are The Signs That A Purge Valve Is Failing

It’s a good idea to check the engine light. Otherwise, the car is hard to start, or the engine performance is terrible. Besides that, there could be an emissions problem that caused the test to fail.

Final Verdict – P0446 Chevy

Typically, any malfunction with your EVAP system might cause a cascade of issues. You’ll almost always notice numerous codes, especially if the problem is caused by a leaking fuel tank or a malfunctioning charcoal canister. Again, you want to address these issues right away so that you aren’t caught off guard by another code that you overlooked because the check engine light was already illuminated.

P0446 Chevy is an issue code that can be difficult to identify immediately. To figure out what’s wrong, you’ll have to run through a set of tests. You can use an advanced scan tool to diagnose the P0446 Chevy and acquire real-time powertrain control module data if you have one on hand. This tool can also switch the EVAP canister vent solenoid on and off to show you where the leak originates by enabling the vent and purge.

Related Posts

Leave a Comment