Toyota 4Runner P0446: EVAP Vent Control Circuit - Malfunction

The most common problem code for the Toyota 4Runner The Code P0446. The trouble code refers to a number you receive when your 4Runner is plugged into an OBDII scanner. It indicates that an issue is occurring with the evaporative emission controller system. This code is often found with P0420 or P0441 codes.

P0446: Evaporative Emission Control System → Vent Control Circuit → Malfunction

Normally, P0446 does not pose a threat to vehicle driveability. Certainly anytime the service engine soon light is on, it’s good to deal with it as soon as possible though. This is usually accompanied by P0442. Another common code for trouble is P0420. It often comes with P0446.

Toyota 4Runner P0446 OBDII Code Symptoms

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. You may notice a gas smell after using P0446. It is related to fuel vapors.

Toyota 4Runner P0446 Meaning

P0446 stands for a universal OBDII Trouble Code. The code can be used regardless of the make and model of your vehicle. 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 to ignite the normal combustion process. 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.

4Runner P0446 Trouble code Causes

The P0446 code can be triggered by many factors in your Toyota 4Runner. These are some of the most frequent problems that can trigger the P0446 trouble code in your Toyota 4Runner.

• 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. This can lead to the code P0446. You should look for a hole or a tear in the fabric.
• 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. You may not get the message but a P0446. This will save you time and money.
• 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 Diagnoses- Toyota 4Runner

To diagnose the problem with your Toyota 4Runner's P0446, a mechanic can use a variety of tools. The most commonly used methods to diagnose this code are:

• The mechanic will usually check for any additional trouble codes. A mechanic will usually check for additional trouble codes to help diagnose the problem. 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. These include the line and purge valve.
• 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.

P0446 Most Common Fixes

These are some of the most popular 4Runner P0446 fix:

• Replacing the gas cap
• Replacement for EVAP Line
• Replace charcoal canister
• Change 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 check your gas cap.

You will need to solve the problem quickly. We trust this helped. Please leave us a comment below if you have any suggestions. Enjoy your day.