I was wondering if someone could tell me what a "Canister Purge Solenoid" (they also called it "Canister Vent Solenoid") and a "Fuel Gauge Sender" (they also called this "Fuel Level Sensor") are?

I have a 2005 Mustang V6 4.0L and the check engine light came on recently and the codes given are for the items above. My car appears to drive as it always has. Are these items that could affect gas mileage?

I appreciate any help. I would like to know a little more before I spend the $867 to have the car repaired.

 

http://iihs.net/fsm/?dir=8

Canister purge valve is in the rear under the spare tire well
or up under the hood near the drivers strut tower...
A tube goes to the intake from it...
The fuel level sender is in the fuel tak and there are 2 of them...