How to Diagnose a P0443 Code

If a check engine light appeared for a P0443 code, find out how to diagnose it yourself with these tips.

What Does Code P0443 Mean?

Mechanic under the hood reviewing what can cause code P0443

Code P0443 is an EVAP purge solenoid circuit code. This code means the computer can’t communicate with the purge valve solenoid. Since it’s a circuit code, it also means the problem is not with the vacuum side of the purge valve. There could be a problem like faulty wiring, a bad electrical connection, or the purge solenoid itself is defective.

More about the parts of the EVAP system

How to Diagnose Code P0443 Yourself

Steps to diagnose code P0443

  1. Check the Gas Cap

    When a check engine light turns on in your car for an EVAP code, we recommend checking the gas cap first. Make sure the gas cap ratchets and secures fine, and check the gasket for damage like tearing or broken pieces

    How to inspect the gas cap

  2. Check the Fuses with a Test Light

    Connect a test light and check the fuses. See if there are any blown fuses, and fix and replace those first.

    More on how to test a fuse with a test light

  3. Find the Purge Valve Solenoid

    The purge solenoid needs vacuum, and will be attached to the intake manifold. It will also have a vacuum line connected toward the gas tank. In this example, the purge valve is mounted directly to the intake manifold.

  4. Check the Purge Solenoid’s Wiring and Electrical Connector

    Visually inspect the wiring. Make sure there are no signs of damage, like a rodent that chewed through the wiring.

    Make sure the electrical connector is connected tightly with no loose connection. Disconnect the electrical connector and check the terminal ends. Look for signs of discoloration, like green corrosion, or other signs of damage like spread terminals.  

  5. Test the Electrical Connector with a Test Light

    An advanced scan tool and test light can help you test the electrical connector. A scan tool that can conduct special tests with the EVAP system will allow you to tell.

    Connect a test light to ground, and test the electrical connector for power, which is an orange wire in this example.

    Then connect the test light to the positive battery terminal, start the vehicle, and check the ground side, which is a green and white wire in this example. Then start the test on the scan tool and select the increase command. The test light should be fluctuating like in the video at 2:30. You’ll only be able to do this for a short time before the test times out. Then you should be able to tell if power on the ground is reaching the connector.

    If the electrical side is working, then the purge solenoid valve is defective and needs a replacement.

How-to Videos to Replace a Faulty Purge Valve Solenoid and More

We have thousands of how-to videos with general tips and step-by-step instructions for model-specific repairs. Follow the tips from our expert mechanics and learn how to replace a purge solenoid and more yourself.

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How to Diagnose a P0443 Code Yourself - Expert Tips - 1A Auto
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How to Diagnose a P0443 Code Yourself - Expert Tips - 1A Auto
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If a check engine light appeared for code P0443, find out what to do and how to diagnose it yourself with these tips from the expert mechanics at 1A Auto
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