Answer to a pm sent 02/26/2013..
By far the most common failure item having to do with the EVAP emission system failure is the canister purge solenoid...I have seen lots of them posted as bad...
Ebay is probably the best place to get one (price wise)...
Dorman 911 803 Solenoid Canister Purge Fits Hyundai Kia Each | eBay
Summit Racing is a very reputable company also...
Here's a cut and paste I have edited and used before to answer the same question as yours...
Start...
First of all, it does absolutely no good to clear codes without properly diagnosing the code and correcting the problem that caused the code to set in the first place. It will only result in the code returning again and again as you can now see.
You must also know how the system works and what failure is indicated by the code. Please note that fault codes NEVER tell you what parts to replace. Then you must know what conditions in the system cause the code to set in order to perform a valid diagnosis of the system.
failure.
With all that said, let's take a look at the code itself:
Diagnostic Test Code (DTC) P0496 is defined by SAE J2011 as "Evaporative Emission System High Purge Flow".
Purge flow is determined by the ECM (engine control module) by looking at the Fuel Tank Pressure (FTP) sensor. When there is little or no purge flow, the FTP sensor will read high pressure. If there is too much purge flow, the FTP will read low pressure.
The code is clearly stating that there is too much purge flow (or low pressure/high vacuum in the tank). The people that have been trying to diagnose this problem apparently do not understand this. Leaks in the system like leaking lines or defective fuel caps will cause the pressure to be too high when it is SUPPOSED to be low and will set a code P0455, P0456, or P0457. Smoke testing and fuel cap replacement is what you do for THESE codes, NOT code P0496.
In simple terms, what is happening here is that the PCM is telling the EVAP system to stop purging and it is continuing to purge anyway. This is usually caused by a stuck open Purge Control Solenoid Valve (PCSV).
They should be looking at why the pressure is low or vacuum keeps increasing when the PCM is telling it to stop.
Pretty much only three things that can cause this code:
> Stuck open PCSV (most likely)
> Defective fuel tank pressure sensor (less likely)
> Defective or mis-calibrated PCM (even less likely)
end...
The high pressure in the fuel tank is holding back the fuel and causing the P03XX codes.
No fuel/little fuel = Misfire of spark plugs.
I'd bet that if you removed the gas filler cap you'd get a whooshing sound from the air the gas tank sucks in when the problem shows up.
It's like you sucking on a "Coke" bottle...you can suck only so hard then no more..
The fuel pump is sucking gas and can't after it vacuum gets too high... Then little or no fuel gets to the engine and the plugs misfire..
To find it...
http://www.kia-forums.com/2g-2006-2010-rio-rio5/72263-2006-kia-rio-lx-location-vapor.html
and look for Ken99's post and for the item marked #1
This YOU can replace yourself with no tools in a few minutes!!
Dave