Code P0496, Emissions system

Hello,

The code: P0496 - Evaporative Emission (EVAP) System Flow During Non-Purge

Any time a EVAP code comes up it can be triggered by few different components or issue.
This specific code can be due to a faulty EVAP canister purge solenoid. It could be stuck shut and not purging the gases as it is designed to do. It can also be faulty wiring for the valve.
This valve is located under the hoot next to the intake tubing (see diagram below).

https://www.2carpros.com/articles/evap-system-code-repair

Please let me know of any questions.
Thank you.

Just to jump in on this. I have seen this a number of times. The reason it went a week before you set the code again is it takes time to run through the monitors before it starts checking this system again. When you clear codes some scan tools will wipe what is called the adaptive numerator or if you clear the codes by doing a battery disconnect then this wipes this information as well and then ECM will not run these tests on this system until that is learned again which takes about a week.

I attached the info on this code so that if you have a scan tool then we can monitor the fuel tank pressure sensor to make sure there isn't something else going on.

If your pressure is dropping, which means the voltage is higher than 1.9 volts then you most likely have an issue in the line going from the tank to the valve.

I attached the testing for the code and then how to replace the purge valve just to be sure this is what you did and replaced.

Then to check this line, we need to unhook the line at the purge and the tank and use a hand pump and pull the line into a vacuum and see if it will hold a vacuum. You are going to have to use a rubber plug on the end at the tank, but you should be able to pull it into a vacuum and have it hold.

I suspect you will not be able to get it to hold a vacuum which means you have a crack in the line.

Let us know what questions you have or what you find. Thanks

Okay. That is great info. If this is throwing this code now, that is telling you that the converter is not reducing the emissions enough and the vehicle is potentially putting out too much damaging emissions.

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Basically, you can try to use those chemicals to clean this out and that may resolve the issue. However, if it doesn't then this could be a sensor issue. So, if he found that the rear sensor was causing the issue, I imagine that is because it was saying that the sensor was not reading properly. That is usually due to a sensor issue, but it is possible that the sensor is accurate, and the converter has failed.

So, if this code does not clear after running that chemical through it then the testing below needs to be completed in order to figure out what is happening.

Let us know what happens. Thanks

If the converter is new, then the o2 sensors are likely the issue.

Basically, the way this works is the downstream sensors are telling the PCM that the emissions have not been reduced to the proper amount, so the PCM thinks the converter is not doing its job.

This is normally a converter issue but if the upstream o2 sensor is not reading correctly and it is low, and the downstream sensor is reading correctly then the PCM would think that the converter is not reducing the emissions properly. Also, it can be reverse where the upstream is correct and the downstream is reading high incorrectly.

So, if you have a scan tool that can monitor the o2 sensors then that is the best way to determine this.

If not, then we should just replace all the sensors as we don't know if it is up or down stream that is causing the issue.

As for the C code. It is possible that this is causing that one, but we need to start with the o2 sensors and see if that resets.

If it does, then we need to get a new post started for it because that would not be related to this.