Chevy Silverado P0446 OBDII Code Diagnosis

The most frequent trouble code with the Chevy Silverado The Code P0446. This trouble code is the number given to you by an OBDII scanner when you connect your Silverado. The trouble code P0446 indicates that the evaporative emissions control system is failing. This code is often found with P0420 or P0441 codes.

P0446 Chevy Silverado

P0446: Evaporative Emission Control System Vent Control Circuit Malfunction

The P0446 problem is not usually a serious threat to your car's driveability. Certainly anytime the service engine soon light is on, it’s good to deal with it as soon as possible though. It's often associated with P0442. See Chevy Silverado P0442 OBDII Code for more. Another common trouble code is P0420.


Índice de Contenido
  1. Chevy Silverado P0446 OBDII Code Symptoms
  2. Chevy Silverado P0446 Meaning
  3. Silverado P0446 Trouble Code Causes
  4. P0446 Diagnostics- Chevy Silverado
  5. Most common P0446 fixes

Chevy Silverado P0446 OBDII Code Symptoms

Chevy Silverado P0496 OBDII Code
In most cases, P0446 will only be a check engine light.


The P0446 code is usually not accompanied with any obvious symptoms. You will see the light on your service engine shortly, but this is typically it. A slight drop in fuel economy is not uncommon. A slight gas smell may be caused by P0446. Because it is related to the fuel vapor treatment system, P0446 may also cause a slight gas smell.


Chevy Silverado P0446 Meaning

P0446 stands for a universal OBDII Trouble Code. The code is universal, meaning that it will be the same regardless of the make and model of your vehicle (Silverado). Technically, the code stands for:

Evaporative Emission Control System – Vent Control Circuit Malfunction

The EVAP system collects fuel vapor from fuel tanks and then sends it to the intake of the engine in order for them to ignite in normal combustion. The P0446 OBDII code will be thrown if the EVAP controller vent circuit doesn't respond to ECU.


Silverado P0446 Trouble Code Causes

You can have the Chevy Silverado's P0446 trouble code trigger for many reasons. These are some of the more common issues that can trigger the P0446 trouble code in your Chevy Silverado:


  • Vapor Canister Purge Valve– One of the most common causes of the P0446 code is the vapor canister purge valve.
  • It’s really easy to replace. There are some clips you will need to look for and then remove.
  • Evap Hose– The hose that carries the fuel vapor from the fuel tank to the intake manifold can begin to leak. The P0446 code will be generated. It should have a tear or a hole.
  • A Faulty Canister of Charcoal– The charcoal canister is often the cause of P0446.
  • Fuel Tank Sending Unit– It is possible for the fuel tank sending unit to go bad. This could cause line pressure to drop and throw off the code.
  • Fuel Cap– A bad fuel cap can cause the code to be thrown for sure. Often, you’ll get a message informing you that the fuel cap is off even when it is on. It may be worth your time to get that message and a P0446 to check if the fuel cap is working.
  • Fuel Filler Neck– There is often a gasket where the fuel filler neck connects with the gas tank. The gasket may dry out especially if the vehicle is in dry conditions. When it dries out, the fuel tank can’t hold pressure anymore.


P0446 Diagnostics- Chevy Silverado

To diagnose the problem with your Chevy Silverado's P0446, a mechanic can use a variety of tools. The most commonly used methods to diagnose this code are:

  • The mechanic will check to make sure there are no other codes. It is easier to diagnose problems if there are more codes. That’s because when they appear together in certain combinations, there will often only be only a few conditions that will throw any combination of codes at one time.
  • Once the mechanic has determined the trouble codes associated with P0446, he or she will usually Take a look at the EVAP system. It includes the purge valve and line as well as the canister.
  • To ensure that the cap can withstand pressure, the mechanic will check it. If you are getting a warning that your gas cap is off, even when it’s on, replacing it will more than likely clear this code.
  • Monitoring and checking the fuel tank pressure is a must.
  • Following the inspections and repairs, the mechanic will conduct two more tests.
  • A smoke test, and they’ll use a scan tool to confirm that the EVAP solenoids and valves are operating properly.


Most common P0446 fixes

P0446 Chevy Silverado Fix

These are some of the most popular Silverado P0446 fix:

  • Replacing the gas cap
  • Replacing EVAP lines
  • Replace charcoal canister
  • Replacing the fuel tank

You should start with the gas caps and move on to the fuel tanks. This is because the gas caps are the easiest to replace and the least costly.

Here’s a great video on How to test your gas tank.

We wish you all the best in finding out why your Chevy Silverado is throwing the P0446 code. This should help. Please feel free to add anything below.

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