1999 Oldsmobile Silhouette. 3.4 V6
Question: Days after rebuilt the engine the check engine light came on do I went to the auto parts to connect the scan and the guy told me the problem was code P0440 but the light has been coming on and out. Thanks.

Answer: The scan P0440 code that is stored in your computer of your Oldsmobile is due to an Evaporative Emissions System problem. It probably doesn't have to do with your engine rebuild, unless you've left an EVAP line disconnected or have pinched the wiring to a solenoid somewhere. The 440 code is a general code and covers the entire EVAP system. It is basically telling you there is a problem with a sensor or solenoid, or that a leak has been detected in the system.

If you're familiar with the components of the EVAP system, I would start by checking the EVAP Vent Valve. Those are known to stick open or closed and will set a code. It is located under the vehicle, back by the gas tank. There will be a line coming from the EVAP Canister going to the valve. Give it a few taps, or remove it and see if there is any debris inside of it. Other problems could be a bad Purge Solenoid, Gas Cap, or even a leaking o-ring seal at the fuel pump. There are many things that would need checking, and a scanner would come in handy.