I am having an issue with a repeated p0440 evap code. I thought I had found the problem when the vacuum line from the throttle body to the evap purge valve feel apart in my hands. The rubber part of the line where it takes the 180 degree turn in to the purge valve had become dry and brittle. It was obvious it had a hole in it before it fell apart. I installed a new line and a new purge valve. I have also changed the gas cap. It was cheap and I was told it was the most likely cause. I am about $50 worth of parts into this and I am still getting the code.


First question: Are all OBD2 codes applicable to all cars or do they very by make and model? I see at least 10 OBD2 codes associated with the evap system. Are all of them applicable to my 2002 Bonneville SE? if not does anyone know which ones are applicable to my car?


Second question: When I follow the line under the hood from the purge valve to the firewall I come to a fitting with a green cap. What is this fitting for? Is that where a mechanic would hook up a smoke machine?


Third question: Is there somewhere I could find a diagram of how this system is supposed to work? I have seen diagrams of the components and general explanation of what the system does, but not specifically how it is supposed to work.


Last question: short of taking it to a garage for a smoke test (into the mechanic too much $$$$ already) any suggestions what my next step should be to solve this problem?


I really do appreciate any help I can get. Getting tired of turning off the check engine light.