My check engine light came on and the service rep said it was caused by a bad Filler Neck which was causing fumes to escape from the fuel filler neck. Is something like this covered under manufacturer extended warranty?

 

I believe that an 80k miles "warranty" exists on all aspects of the emission system (by law) in the USA but not in Europe / UK.
Europe operates a 3 year (but please check) warranty.

Yep the gas / fuel cap can cause the CEL Check Engine Light to illuminate if there is a bad vapour seal between the neck and the cap.
This seal is achieved by means of a gasket which can become damaged over time due to a "sharp" edge or similar on the top of the neck.
Simple solution is remove sharp edge and fit a new gasket which costs a few pence. A new cap is not an arm and a leg job!

However, there are other reasons why the fuel tank pressure may not be being maintained.
Likewise there are many other reasons why the CEL may be illuminated.

Hope this answers your question.
Stuart

 

This problem is often just the gas cap that has been installed incorrectly or not tight enough. On the rare occasion that this has happened the CEL resets anywhere from 1 minute to several days.
It should be covered by your warranty if there is a real problem with the seal. You may just need a new gas cap.

 

They replaced the filler neck under warranty after a couple calls. At first they said it was not covered but the sales rep called again and they ok'd the repair. Definately not a cheap fix after looking at the repair invoice.

 

i agree with gilgorm. i had a similar problem and that resolved it.