P0446 Chevy Silverado: Diagnosing and Resolving EVAP Vent Control Circuit Problem

P0446 Chevy Silverado: If you have a Chevy Silverado, it’s important to keep an eye out for any trouble codes that appear. One of the common codes you encounter is the P0446 in your Chevy Silverado, which relates to the Evaporative Emission System Vent Control Circuit. Don’t worry if it sounds complicated. In this article, we’ll break it down for you in simple terms and provide step-by-step instructions for diagnosing and fixing the problem. So let’s get started!

What is P0446 and How Does it Affect Your Chevy Silverado?

P0446 is a trouble code that indicates a problem with the Evaporative Emission System Vent Control Circuit in your Chevy Silverado. This system is responsible for capturing and storing fuel vapours to prevent them from escaping into the atmosphere. When the vent control circuit malfunctions, it can lead to various issues, including fuel odour, decreased fuel efficiency, and the illumination of the Check Engine Light on your dashboard.

Identifying Symptoms of P0446 in Your Chevy Silverado

Detecting the signs of P0446 can help you solve the problem right away. Here are the common symptoms to watch out for:

  1. Check Engine Light: The first and most noticeable symptom is the Check Engine Light illuminating on your dashboard. If this light comes on, it’s important to pay attention and take action.
  2. Fuel Odor: You may notice a strong fuel odour around your vehicle, indicating potential leaks or problems with the Evaporative Emission System. If you smell gasoline when you’re near your truck, it’s time to investigate further.
  3. Reduced Fuel Efficiency: P0446 can also lead to decreased fuel efficiency. If you find yourself filling up more frequently than usual or noticing a drop in mileage, it could be related to the malfunctioning Evaporative Emission System

Diagnosing P0446 in Your Chevy Silverado

To diagnose the P0446 trouble code, follow these simple steps:

  1. Use an OBD-II Scanner: Plug in an OBD-II scanner, which you can easily purchase or borrow, into the diagnostic port located under your truck’s dashboard. The scanner will retrieve the specific trouble code (P0446) and provide you with valuable information.
  2. Inspect the EVAP System Components: Visually examine the various components of the Evaporative Emission System, such as hoses, valves, and connectors. Look for any signs of damage, leaks, or loose connections. Pay special attention to the Vent Control Valve.
  3. Test the Vent Control Valve: Using a multimeter, check the vent control valve’s functionality. Measure the voltage or resistance to ensure it falls within the specified range. If the valve fails this test, it might be the cause of the P0446 trouble code.
  4. Examine Wiring and Connectors: Inspect the wiring and connectors associated with the vent control circuit. Look for any signs of damage, corrosion, or loose connections. Faulty wiring or connectors can disrupt the proper functioning of the circuit.

Fixing P0446 in Your Chevy Silverado

P0446 Chevy Silverado

Now that you’ve diagnosed the issue, let’s move on to fixing it. Here’s what you can do:

  1. Replace the Vent Control Valve: If the vent control valve is found to be faulty during your diagnosis, it’s best to replace it with a new one. This will ensure the proper functioning of the Evaporative Emission System.
  2. Repair or Replace Damaged Components: If you discover any damaged hoses, connectors, or other components during your inspection, repair or replace them accordingly. Leaks or loose connections can compromise the efficiency of the system.
  3. Clear the Trouble Code: After completing the necessary repairs, use your OBD-II scanner to clear the trouble code and reset the Check Engine Light. This step confirms that you’ve addressed the issue successfully.

Preventative Measures for P0446 in Your Chevy Silverado

To minimize the chances of P0446 recurring in the future, follow these preventive measures:

  1. Regular Maintenance: Adhere to the manufacturer’s recommended maintenance schedule. Regularly inspect and service your Chevy Silverado to keep the Evaporative Emission System in optimal condition.
  2. Check the Fuel Cap: After refueling, ensure that the fuel cap is tightly secured. A loose or damaged fuel cap can cause pressure imbalances in the Evaporative Emission System.
  3. Avoid Overfilling: When refueling, avoid overfilling the fuel tank. Overfilling can lead to excess pressure in the system, increasing the chances of malfunctions.

Cost of Fixing P0446 in Your Chevy Silverado

The cost of fixing the P0446 issue in your Chevy Silverado can vary. DIY repairs can range from $30 to $100 for the replacement part. Professional mechanic costs can range from $150 to $400 or more, including labor and parts. Additional repairs and warranty coverage should also be considered.


Can I continue driving my Chevy Silverado with the P0446 trouble code?

It is generally safe to drive your vehicle with the P0446 trouble code, but it’s recommended to address the issue as soon as possible. Ignoring the problem could potentially lead to increased emissions and reduced fuel efficiency.

Can I fix P0446 myself, or do I need a professional mechanic?

If you have the necessary tools and mechanical knowledge, you can attempt to fix the P0446 issue yourself. However, if you’re unsure or lack experience, it’s advisable to seek the assistance of a professional mechanic to ensure proper diagnosis and repair.

What happens if I don’t fix P0446 in my Chevy Silverado?

If this is not addressed, P0446 could potentially lead to increased emissions, decreased fuel efficiency, and even more serious issues in the Evaporative Emission System. It is best to address the problem immediately to maintain optimal performance and minimize any potential complications.

Is the P0446 issue covered under warranty for my Chevy Silverado?

Whether the P0446 repair is covered under warranty depends on the specific terms of your warranty. Check your warranty documentation or contact your dealership to determine if the repairs fall within the coverage.

Can a faulty gas cap cause the P0446 trouble code?

While a faulty or loose gas cap can potentially trigger a similar trouble code (P0455 – Evaporative Emission System Leak Detected), it is unlikely to directly cause the P0446 code. However, it’s still important to ensure your gas cap is in good condition and tightly secured to maintain the integrity of the Evaporative Emission System.


Dealing with the P0446 trouble code in your Chevy Silverado’s Evaporative Emission System Vent Control Circuit doesn’t have to be overwhelming. By understanding the symptoms, diagnosing the issue, and following the step-by-step instructions provided in this article, you can confidently resolve the problem. Remember to perform regular maintenance and take preventive measures to keep your Chevy Silverado running smoothly. Drive with peace of mind, knowing you have successfully addressed the P0446 trouble code.