Nissan Repair: Nissan Pathfinder, canister purge valve, gasoline vapors

Question
I have "check engine" warning light.  I says the problem is Evacuation control system sensor (PO450) and Vent Control Valve needs to be checked.  What are these warnings and are they important to repair.  What is the potential cost to repair?

Answer
Mike,

The evaporative control system is used to contain gasoline vapors and there is a valve that controls the vapor when the engine is started.  It bleeds off vapor and allows it to be burnt off.  A couple of hundred bucks if you have it taken care of.  The vapor vent valve is about $100 bucks and another $100 for labor.  Also, you could have a damaged hose.  But, most of the time it is the canister purge valve on the or close to the canister.  The canister is in the back of the car close to the gas tank.  Try rockauto.com or courtesyparts.com or check with your local dealer for a little more money.  But, if they have to order it I just do it on line.