P0496 code: Mechanic advice to diagnose & fix

P0496 Code
Evap Flow During a Non-Purge Condition

If your Check Engine light is on and your scan tool lets you know your car has a P0496 code, which is an Evaporative Emission Control (EVAP) System code, this means something is causing fuel vapors to escape from your car that shouldn’t. 

In this video, our mechanic shows you how to diagnose the problem that triggered P0496 using common EVAP purge valve tests. Watch now:

Check Engine Light? EVAP Flow During Non-Purge Condition – Code P0496 

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What is code P0496 and what does it mean? 

Code P0496 is defined as “EVAP Flow During Non-Purge Condition”. This means something has gone wrong in either the emissions or fuel systems

What typically triggers this code is an EVAP purge (or EVAP purge volume control or canister purge) valve that isn’t working correctly. 

When an EVAP purge valve is working properly, it is closed. The most common cause of P0496 is an EVAP purge valve that is stuck open, which allows fuel vapors to escape. 

How serious is a P0496 code?: Is it OK to drive with P0496? 

Other than the Check Engine Light staring at you, you may not have any noticeable changes in your vehicle with code P0496. However, as with most automotive issues, it’s best to address a problems as soon as possible to prevent any further damage, or unnecessary vehicle emissions.  

What are common P0496 symptoms? 

  • Your Check Engine light is on 
  • You may have difficulty starting your car, but aside from the Check Engine light, this code usually doesn’t have many noticeable symptoms 

What causes P0496? 

  • Most common P0496 cause: Failing, bad, faulty, or leaking EVAP purge valve 
  • Leaky EVAP system hose 
  • Faulty or disconnected EVAP system connectors 

How do I diagnose and fix P0496? 

Check your gas cap 

The first thing you should check whenever your car has a P0496 code is your gas cap—make sure it’s not loose because a loose gas cap can trigger a P0496. 

If your cap isn’t loose, you should also unscrew and inspect its seal to make sure there isn’t anything inside the cap that could be causing the problem, such as damage or debris. 

Test the purge volume control valve for a “Stuck Open” condition 

With the engine off, remove the hose from the fuel tank that connects to the purge volume control valve (in most vehicles, this valve is normally located near or on the intake manifold), and disconnect the valve’s electrical connector (beginning at 1:24 in the video above). 

With the engine running, use a vacuum gauge, or even your finger, to find out whether any vacuum is coming from the valve where the hose was removed. If there is vacuum, this means the purge valve is stuck open, allowing fuel vapors to escape (if it wasn’t stuck open, and working correctly, there wouldn’t be any vacuum during this test). 

If this test confirms the purge valve is stuck open, it will need to be replaced

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Perform an EVAP purge valve leak test 

You can also do a similar test to the “Stuck Open” condition test with the engine off, that will also help you determine whether a purge valve is bad. 

With the engine off, remove the purge valve by using a screwdriver to gently pry the bracket, and once the valve is loose, slide it out (1:58 in the video). 

With a hose connected to the valve, you can either try blowing through it from either direction or connect a vacuum pump to test whether air comes out (2:17). Make sure everything is connected properly before testing this. If air does come out, that means there’s a leak, and the purge valve needs to be replaced. 

Our mechanic shows you how to install a new purge valve at 2:56 in our P0496 video. 

After replacing the purge valve, use a scan tool to clear the P0496 code and drive your car to make sure everything is working properly. If you have a more powerful scan tool, you should be able to test the EVAP system, too.

Optional tools for testing: 

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