Driving down the road and you see "Check Gas Cap" warning come up on the Drivers Info Center (DIC)...take heart, it's an easy fix
and does not take much time or money to repair yourself.
First, check your fuses and your gas cap. The cap should be on good and make sure it's secure. Tank up and drive your car for about 50 miles. If the code does not clear you should replace your gas cap. I purchased one from my local Chevrolet dealer for $22.
Secondly, if after tanking up and replacing your gas cap the warning does not clear, then it's time to use your trusty code reader and see if you can't read and clear the code. If you don't have one you can purchase them at your local parts store for about $50.
Plug it in the OBD adapter located under the driver’s side dash.
Follow your reader’s instructions and read the codes.
In my case I had a P0449 and a P0455. P0449
Evaporative Emission Control System Vent Valve/Solenoid Circuit Malfunction and P0455
Evaporative Emission Control System Leak Detected (gross leak)
I tried resetting my codes, but they would come back within seconds. The next step is purchase a new Fuel Vent Solenoid from your local dealer. In my case it was about $25. GM also recommends an upgraded harness ($30)...but it was not needed, so I will return it.
The Fuel Vent Solenoid is located on the passenger side tank near it’s top and is easy to get to. I removed my rear tire, jacked up the car, placed jack stands and chocks (I'm super cautious under a car).
Once under the car this is what you will see, and I have my finger on the part:
Remove the Vent Hose (it runs to your emissions canister) using a pair of pliers. You can rotate the clamp if needed to access the dog ears to open the clamp.
Unplug the power connection
Slide the Vent Solenoid Assy of its bracket. Although it looks like it would slide towards the front of the car it does not. Simply lift the back of the assy high enough for the dog ear to clear the back of the bracket and slide toward the rear of the car. The pic below shows you how it mounts and the dog ear location.
Put the new Vent Solenoid Assy back on by placing it on the bracket and slide it towards the front of the car. You will hear it click in place. Plug the power plug back in and reconnect the hose.
Here is the new one installed.
Now plug your code reader back in and scan for codes. If they come up hit erase.
This is what you should now see on your code reader. No Codes and the DIC is clear with no check engine light or warnings.
From start to finish the repair took 20 mins. The cost of the parts, including gas cap was about $50 and if the harness is needed it's about $80. If you don't have a code reader add another $50. Only tool needed is a pair of pliers.
In all this is a simple repair and does not cost much in terms of time or money to do yourself.
I hope this helps,