Engine Code - P440

Hey All,


So my check engine light has been on for awhile. I got it scanned and came back to P440 (Evap.).
The mechanic visually inspected the components (gas cap, charcoal canister, all tubes / lines running into the system) and couldnt figure out the problem. I really want to fix the problem but I don’t want to take it to the dealership. Has anyone else had this problem? Another thing I noticed is that the tank never makes a sound when removing the gas cap. Does anyone have any idea of what’s going on?

2002 Chevy Cavalier 2Dr. Coupe Z24
103,000 KMS

Thanks

Lewis

Also would gas mileage by affected by a malfunction in this system?

Thanks

Lewis

[Cold_Silence]

I had P0440 on my 96 cav, it came on and off periodically. I didnt worry too much about it, prolly was a leaky evap hose or the actual evap can was bad. It shudnt effect anything but the atmosphere.. If u get pulled on over and ur car scanned and they see that u may get a fine though.. It would not pass the emissions test dealy but i didnt bother with it. Only bitch about that code is ur rad fan runs 24/7!! I had to pull the relay..

[sweetpolly]

Hello and I have some news on your problem with the 440 code. I have a 2003 Cavalier and I too had this code show up on my car. I replaced the gas cap because the gasket was bad on it. The place I bought it from cleared my code out for me for free. Low and behold it came back on a day later. I went and had a special test done called a "smoke" test to find the "leak in the emissions system. The problem was a vent solenoid. The part number is (15215729). When it goes it causes the vacuum sensor not to sense if gas vapors are escaping. I had the extended warranty but the total cost was about $93.00. I hope this helps anyone with this problem. So if you get the "smoke" test done it is approximately $55.00 plus the part which was about $28.00. Well good luck to all.


sweetpolly

Originally Posted by LEWISM

Hey All,


So my check engine light has been on for awhile. I got it scanned and came back to P440 (Evap.).
The mechanic visually inspected the components (gas cap, charcoal canister, all tubes / lines running into the system) and couldnt figure out the problem. I really want to fix the problem but I don’t want to take it to the dealership. Has anyone else had this problem? Another thing I noticed is that the tank never makes a sound when removing the gas cap. Does anyone have any idea of what’s going on?

2002 Chevy Cavalier 2Dr. Coupe Z24
103,000 KMS

Thanks

Lewis

After the smoke diagnostic was done and the part was fixed did the code clear itself? Or did you have to manually clear the code?

Thanks

Lewis

Do you think I should go right to the smoke test or buy a new gas cap?

[sweetpolly]

To be honest I don't know if the code cleared itself or if they had to use a code scanner to clear it. The best way is when you have the part replaced by a mechanic they should have a scanner that can clear the code. If you replace it I would suggest calling a parts place near you. Most have code scanners that they use to diagnose your car and mine where I live cleared mine for free. I hope this helps you out. All I can say though is that the engine light is off, has stayed off since I had the part replaced. I was also told by a mechanic that taking off the battery wire and letting it sit for a spell isn't the way to do it most times. Your car if it has a code that shows a problem is stored in the computer and the only way to get rid of it for good is to have it cleared by a scanner.

Sweetpolly

Originally Posted by LEWISM

After the smoke diagnostic was done and the part was fixed did the code clear itself? Or did you have to manually clear the code?

Thanks

Lewis

[shakewell]

The shop would've cleared the code after they fixed it.

About the original problem - when the person scanned and found your code P0440, did he clear it or just send you on your way. If he didn't clear it, it might be a one time thing where you filled the fuel with the engine running or something like that.

I would clear the code, then drive it until it comes back on. When it does, scan it, make sure it's the same code, then start with the gas cap.

[sweetpolly]

In a prior posting I stated I had my parts store clear the code then when it returned a day later I went and had it rescanned and it came back the same code.

In response for Lewism....As for the smoke test....I would have it done for the simple fact that replacing the gas cap would be okay just like with my car but it didn't fix the overall problem with the vent solenoid that went bad. And yes I do figure that the mechanic will clear your code out after fixing your car. I wasn't in the shop per say due to insurance reasons customers can't be back there that is the only reason I can't tell you if they cleared the code or if it did it on it's own due to being fixed.

sweetpolly

Originally Posted by shakewell

The shop would've cleared the code after they fixed it.

About the original problem - when the person scanned and found your code P0440, did he clear it or just send you on your way. If he didn't clear it, it might be a one time thing where you filled the fuel with the engine running or something like that.

I would clear the code, then drive it until it comes back on. When it does, scan it, make sure it's the same code, then start with the gas cap.

[jakegday]

so what exactly is it about a gas cap missing that causes the check engine light to come on?? i havent had a gas cap in nearly 3 years and my CEL hasnt come on once because of it......

[sweetpolly]

depending on the year of the car, when the gas cap is off it sends a message to a pressure sensor letting you know that the cars gas cap is off. That is what I have been told by the auto place I shop and a mechanic that works on my car.

Sweetpolly

Originally Posted by jakegday

so what exactly is it about a gas cap missing that causes the check engine light to come on?? i havent had a gas cap in nearly 3 years and my CEL hasnt come on once because of it......

[shakewell]

The entire fuel system on most newer cars is a closed system - including the fuel tank. In the days of yore, the fuel tank was just a big bucket from which the fuel pump drew fuel. Now, the fuel tank is part of the emissions system where gas fumes are routed back to it. If the computer detects a pressure drop, it assumes you have a leak somewhere in the sytem (it has no idea where). It can even give different codes depending on whether it is a big leak or a small leak.

That's why not having a fuel cap on while the engine is running can cause a check engine light. If yours isn't coming on even if you don't have a cap you either:

- dont own a car that checks the pressure
- have something preventing the system from working properly

[jakegday]

hmmm, this feature must not have been put in all cavaliers in 98.....
and if for some reason my car DOES have this, and its not working properly, wouldnt that also trigger the CEL?

[shakewell]

A 98 should be checking for evap leaks, but who knows. There are plenty of explainations - could even be that the bulb is out. But it doesn't really matter. It would be interesting, though, to see how the car would change if you bought a cap for it. Might be a power difference, mileage difference, no difference?

[jakegday]

maybe, i know the lights not burnt out cuz it comes on for a second or 2 every time i start the car, it has also come on a few times in the past cuz of actual problems it was having