That's the port under the dash that a coded reader plugs into. Smog check stations use it in addition GM's tech 11 use it.

 

Who told you to put it on "lightly"? Turn it till it clicks a few times. (Thats what the clicks are for; to tell you its on tightly enough)

As for the code, typically a CEL will store a history code for retrieval, even after the light goes out. Code readers are relatively cheap at your local auto parts store. You might consider getting a code reader and then posting up what it says so someone on here can help you interpret it. Anything else is pure guess-work.

 

The "lightly" part was saying to not push down on it while you are turning. But you turn until it clicks.
An inexpensive code reader (<$50) is the best investment you will ever make in tools. It should last many, many years and works with all cars after 1995. Even if you don't know how to use a screw driver, you need a code reader so that you know what the real problem is before you go to the dealer. You plug it in to the socket, press the bottom of the start button to put the car in run without starting, read the codes, come back inside and go to http://www.obd-codes.com/ and find out not only what's wrong but often get instructions on how to easily fix it yourself. Any code reader will also reset any codes that were set which will turn off the Check Engine Light until the issue returns.

 

Well, here we go again. I got my car out yesterday ( I haven't driven it but maybe once or twice since my last post on this in June) to go on a cruise with my car club. I went down early and filled the tank up with V-Power at Shell. I got up the road about a mile to meet the rest of the club. When we took off, the engine light came on. Like it says in the book, "Did you recently put gas in the car?"

Heck yeah!! About a mile up the road. Everyone stopped while I fiddled with the cap. But I couldn't get the light to go out so I took the car home and got my other Vette out and caught up with them later. I was only about a mile from the house when I turned around and went home.

When I caught up with them, they all said I should have just driven it. The engine light staying on- only shows some mild emission flaw and it won't hurt the engine. Even one of the retired GM guys said that.

I messed with it all night after I got home and I couldn't get the light to go out. So, I guess I am due for another gas cap. This stuff gets old.

 

I should have pointed this out when this started several months ago. When the light comes on it takes many cold start tests to get the light to go out. It should not go out the instant you tighten the cap. If it does that is just coincidence. You can keep buying gas caps or you can get a $25 code reader or just get a free reading at many auto parts stores and find out what the real issue is. There are hundreds of possible causes for a CEL. The gas cap loose is just a common one.

 

For all that hassle, it might make sense to just go to a NAPA store and get a new Stant gas cap. Even my Walmart has mine. It's $12 and gets you away from the lousy oem cap. I got a locking one, but they make it both ways. Also, the light is not designed to go out as soon as the cap is put on correctly. As stated above, a few start/run cycles are required with no problems in order for the light to go out.

Also, if you know that the gas cap is causing the CEL, there is nothing wrong with going on the cruise with the other Corvettes.

 

Another possible thing.

im not talking from experience, but from what I read on the forum.

That you shouldn't top off your tank, when you fill up.

something about, gas tank evap line losing pressure/flow causing CEL.

curious, did you get the CEL, after filling up?

 

I just went thru the same situation with my '05 so here's the possible (probable) solution. First, as others have noted, read the codes. Most likely, you'll see PO455 which is Evap System large leak & PO449 Evap Control System vent/valve solenoid. The 449 code is the key....indicates that the valve solenoid (also referred to as the EVAP Canister Vent Solenoid) has gone bad. Allows evaporation fumes from the fuel tank to vent to the outside air, thus the error message confusion with a loose gas cap. It's an easy DIY fix.....this is not the canister in the engine compartment. It's located in the right rear on the inside of the chassis above the rear axle. I got the part from Rock Auto (their p/n CVS56) for $17 bucks plus shipping; bought a new Delco gas cap from them at same time for about $15 bucks, just to be safe. I also had the "gas cap" letter from GM, which turned out to be a joke. I had stopped by a local dealer & asked for a replacement cap. Their message was that they first had to do a diagnostic check (for $90 bucks) & if it was something besides the gas cap (which it was), then I'd have to pay for the diagnostic check plus that work (the vent solenoid). I told them "no thanks" & did the job myself for about $35 with the shipping. There's a really great post on the Forum for the DIY fix with pictures....do a search for "DIY Fix for "Loose Gas Cap" indicator aka code PO440". Hope this cures your ills.

 

Thanks for the suggestion. I don't top off. I learned that the hard way the first time I tried it when I bought the car a couple years ago. Once the gas comes up and the nozzle clicks off--that's it. I stop putting gas in.

And yes. I filled up the tank with V Power and we met at a Tractor Supply about a mile away from the gas station. After everyone got there we left to go on our cruise and within a minute or so, I got the engine light. It doesn't flash. It stays on all the time.

Coincidentally, last fall, when I was putting it in the garage, the light came on. A new Delco cap fixed the problem immediately.

And last June, when I started this thread, I had gotten gas, gone home and got the light when I was pulling it in the garage. I fooled with the cap and the light has been out ever since- until yesterday. I guess I'll call NAPA and see if they have one.

 

Well, I psyced it out. I guess my old gas cap got scared and straightened itself out. Here's what happened.

I went over to NAPA and got a new gas cap. I tried it on the car and it fit perfectly. Before I started the car I thought, "OK. I'll give the old one one last shot. So, I put the old cap on, started the car and after a few seconds, the engine light went out.

I guess you guys were right. It probably just took a few starts to reset the deal. So, now that I feel a little stupid for being a pest, I guess I'll sneak out of here and behave myself.

Thanks for all your help again.

 

By the way....... I'll save the NAPA just in case I need it again.