GMC Sonoma P0446: EVAP Vent Control Circuit → Malfunction

The most frequent trouble code with the GMC Sonoma The Code P0446. This trouble code is the number given to you by an OBDII scanner when your Sonoma goes into diagnostic mode. It indicates that an error has occurred in the evaporative emission controller system. This code is often found with P0420 or P0441 codes.

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. Another common code for trouble is P0420. It often comes with P0446.



Índice de Contenido
  1. GMC Sonoma P0446 OBDII Code Symptoms
  2. GMC Sonoma P0446 Meaning
  3. Sonoma P0446 Trouble Code Causes
  4. P0446 Diagnosis - GMC Sonoma
  5. The Most Popular P0446 Fixes

GMC Sonoma P0446 OBDII Code Symptoms

GMC Sonoma P0446 OBDII Code
Most often, P0446 will only be a check engine lamp.


Most commonly, the P0446 code does not cause any symptoms. Although the service engine light may come on soon, that's usually all. It is possible to notice an increase in fuel consumption, but it is unlikely. A slight gas smell may be caused by P0446. Because it is part of the fuel vapor system, P0446 may also cause a slight gas smell.


GMC Sonoma P0446 Meaning

P0446 GMC Sonoma

P0446 stands for a universal OBDII Trouble Code. It means that no matter what make or model vehicle you have, this code will be the same (Sonoma). Technically, the code stands for:

Evaporative Emission Control System Vent Control Circuit Malfunction

The EVAP captures any fuel vapor in the fuel tank, and transmits them to engines intake for ignition. The EVAP control control circuit will not respond to an ECU if it detects a problem with the vent control circuit. This will cause the engine's service light to illuminate and throw the OBDII P0446 code.


Sonoma P0446 Trouble Code Causes

GMC Sonoma P0446 Diagnosis

You can have the P0446 Trouble Code trigger in your GMC Sonoma. The most frequent problems that trigger this code are:


  • 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. You will need to locate and take out a few clips.
  • 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.
  • The Faulty Charcoal Caister– 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. It can cause a disruption in the line pressure, throwing 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. It is possible for this gasket to dry, particularly if vehicles spend a lot of time in dry environments. When it dries out, the fuel tank can’t hold pressure anymore.


P0446 Diagnosis - GMC Sonoma

To diagnose the problem with your GMC Sonoma's P0446, a mechanic can use a variety of tools. These are some of the common diagnostics that can be done for the code

  • Commonly, the mechanic will check for any additional trouble 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.
  • The mechanic will normally determine what trouble codes are associated with P0446. Check out the EVAP System. These include the line and purge valve.
  • A mechanic will examine the gas cap and verify that it is able to withstand high pressure. 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.
  • The mechanic will then perform the following tests after completing the above-mentioned checks:
  • A smoke test, and they’ll use a scan tool to confirm that the EVAP solenoids and valves are operating properly.


P0446 GMC Sonoma Fix

Below are the top Sonoma P0446 fix options:

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

It is best to begin with the gas cap, and then work your way up to the fuel tanks. The gas cap is the most difficult and cost-effective item to replace.

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

We wish you all the best in finding out why your GMC Sonoma is throwing the code P0446. This should help. Feel free to add anything below. Enjoy your day.

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