Check gas cap

[Brae99]

any quick fixes or wht do i need to do? thank you

[1tinindian]

Remove the corrosion from the sealing surface on the filler neck and replace the cap with a new one.

Leon

[Ken_W]

This is a common problem, and can be caused by one or more of several factors:

1) Bad seal between gas cap and filler neck, caused by corrosion on filler neck or old rubber on gas cap. To rule this out, sand the corrosion on the filler neck (if you see some) with a piece of sandpaper held over a flat block (so that you sand evenly and don't create gaps). Unless it is heavily corroded, it shouldn't require much sanding (you're only trying to clean it up a bit). Then buy a new gas cap (should be able to get a genuine AC-Delco or Delphi one for around $15) and replace. Drive the car a couple of times if the code does not immediately go away -- sometimes it takes time to go away in this scenario. Note that the odds of this solving your problem are only 50%, but for $15 it is a cheap and easy first thing to rule out before trying anything else.

2) Old canister purge solenoid is not opening/closing fully. Replace solenoid. Can get one for around $20-$25 if you shop around, and can replace in five minutes using a basic socket set. It is on the top-rear of the engine on the driver's side (if supercharged engine -- might vary for non-supercharged, but part is the same). When I replaced this, my gas cap code went away immediately and never returned. The ACDELCO Part # 214642 looks like this:


3) Fuel vent valve. Underneath the car, on the driver's side, just forward of the rear axle. Must raise rear of car to replace. I did it in my drive way by putting the rear of car on jackstands. Mine had heavy corrosion and was tricky to replace, but I eventually got it done (there is a blow-by-blow thread about it here at the club, with pictures). Replacing this did not solve my problem, but for some people it does. (Note that I replaced this before I replaced the part in #2 above.) This will take you 30-90 minutes depending upon your skill level. The part is ACDELCO Part # 2141363, costs around $21, and looks like this:


4) There are a few other possibilities, but most likely one of the three items above will solve your problem. The good news is that you should be able to fix it yourself for under $60 at most, and probably more like $25.

Please post back with updates to let us know how it goes -- it sucks to type up this kind of info and then never hear back from a guy.

Good luck --

Ken

[mrwildroot]

I thought your write-up was clear, concise and technically informative. Tho not covering any problems for me right now (Thank God!), I will keep it in mind for the future!
Thanks!

MW

[MrJiggy716]

I have the same problem thanks for the write up, I already replaced the gas cap. However I will try replacing those parts one at a time and see if it goes away. A strange quick fix I found is running the car on ACC until the battery goes dead and jumping it, the light goes off and stays off for 2 or 3 months, but always comes back. Even stranger disconnecting the battery for a second and reconnecting it the light goes back on immediately.

[00Beast]

Disconnect the battery cables and touch them together for a minute. It'd get you the same results, without destroying your battery.

[MrJiggy716]

Yes not something I do normally but was left the keys on acc using the car to play some tunes while camping, it died and had to be jumped and boom light off same goes for the tire pressure light that was on ....

[00Beast]

Tire pressure light is easier to fix. First, make sure your tires are inflated the way you want them.

Then toggle to the Tire Pressure menu on the DIC, under Vehicle Data. It will either read NORMAL or LOW. Press and hold the RESET button until it reads "RESET" then release and it will go to NORMAL. Then if a tire gets low, it will warn you again, and you need to repeat this.

[MrJiggy716]

Thanks for the tip. Just out of curiosity wouldn't touching both terminal connects to the battery together cause some kind of problem?

[00Beast]

Not if they're disconnected from the battery first. You might lose your radio presets. What it does is discharges all the capacitors in the system, which provide power to store things like CEL's, etc.

[Ken_W]

These battery tricks are not a cure to the original problem, however. These gas cap warnings come in response to intermittent problems. Depending upon ambient temperature and humidity, they come and go over time. Erasing the code will turn the light off, but eventually the problem will re-occur and then the light comes back on again. Why not just fix the original problem and be done with it?

For what it's worth, the only impact of this problem is that fuel economy drops slightly. VERY slightly. Driveability of the car is unaffected. The only thing most people will notice is the warning light, so each owner will have to decide for himself if the problem is worth fixing.

Ken

[MrJiggy716]

Agreed. Could this be triggering the service engine light as well, mines on and the only code being thrown is the po449 EVAP vent solenoid.

[Brae99]

thank you guys,
Ken, I have bought a new gas cap and it changed nothing so I will be getting the new solinoid thing tomorrow, thank you so much for your help. il let you guys know how it goes!