Volkswagen Passat P0446: EVAP Vent Control Circuit → Malfunction

The most frequent trouble code with the Volkswagen Passat Is the Code P0446. The Trouble Code refers to a number given when the Passat is plugged in to an OBDII scanner. The code P0446 indicates that the evaporative emissions control system is failing. This code is often found with P0440, P0441 or P0440.

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. A common problem code is P0420.

Volkswagen Passat P0446 OBDII Code Symptoms

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. It is related to fuel vapor systems.

Volkswagen Passat 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 (Passat or otherwise). The code is technically:

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. If the EVAP control circuit vent control circuit does not respond to the ECU it will throw the OBDII code P0446 and the service engine light soon will illuminate.

Problem Code Passat P0446

P0446 can occur for many reasons in your Volkswagen Passat. The most frequent problems that can trigger the P0446 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. 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.
• 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. 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 Diagnosis- Volkswagen Passat

To diagnose the problem with your Volkswagen Passat'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. 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. Take a look at the EVAP system. It includes the purge valve and line as well as the canister.
• 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.
• Monitor and check the pressure in your fuel tank.
• 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.

The Most Popular P0446 Fixes

These are some of the most popular Passat P0446 fix:

• Replacement of gas cap
• Replacement for EVAP Line
• 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 check your gas cap.

You will need to find the cause of your Volkswagen Passat throwing the code P0446. This should help. Feel free to add anything below. Enjoy your day.