Is there anyway to check if the EHA Valve is faulty on the car before getting a new one? Any visible differences?

Also I found this:
http://www.thebenzbin.com/mercedes-gas-smell.html

^ Is that the easiest way to remove the EHA Valve?

Trying to finally get rid of this misfire....

Thanks, ps2cho

__________________
2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k