Lower EVAP leak. any ideas??!?!

[greengrandam84]

Well, I have a 2001 GA SE2 3.4 V6 with about 136K mi on it. The service engine soon light has been on for quite a while but seems to be running ok. I have a little scan tool and it says theres a lower EVAP system leak. I've looked in the haynes manual a lot and have searched the engine bay and cant seem to find anything out of the ordinary. I am just wondering if anyone has ever had this same problem / code show up and what the problem actually was?!?!? thanks for any help.

[SE2000]

What code did you get? Most likely your gas cap is loose

[greengrandam84]

im not sure of the number, i have one of those actron small orange scanners from advance auto parts. and it says in the book its a lower evap system leak. i doubt its my gas cap, i clear it and it keeps coming back even after i get more gas and tighten it all the way.... my friend said it might be the O2 sensor, but wouldnt an O2 throw an O2 code?

[HeyDace]

Never heard the term "lower" evap, I'm assuming it refers to a "small leak" detected.
The only thing you can do is check your gas cap, check any and all vacuum and evap lines from the front to the back. If you can't find any damage, then it needs to go to a shop that has the equipment to pressurize and test for leaks.

[BPBAIR]

i have a small evap leak, if you wanna get it checked out at a shop, by all means do it. It will cost you alot of money so get ready for it. They may or may not have to drop the tank. I have had a small evap leak for over 2 years with no problems, i just keep my tank above a 1/4 full 80 percent of the time and the light wont comeon. if i let it go below a 1/4 for a few days the light will comeon a day or two later and in that case i just clear it (this is very rare maybe once every 4 months).

[rixGAphx]

Originally posted by HeyDace
Never heard the term "lower" evap, I'm assuming it refers to a "small leak" detected. Right.

These are the codes for Vapor/Emissions:
P0440 Evaporative Emission Control System Malfunction
P0441 Evaporative Emission Control System Incorrect Purge Flow
P0442 Evaporative Emission Control System Leak Detected (small leak)
P0443 Evaporative Emission Control System Purge Control Valve Circuit Malfunction
P0444 Evaporative Emission Control System Purge Control Valve Circuit Open
P0445 Evaporative Emission Control System Purge Control Valve Circuit Shorted
P0446 Evaporative Emission Control System Vent Control Circuit Malfunction
P0447 Evaporative Emission Control System Vent Control Circuit Open
P0448 Evaporative Emission Control System Vent Control Circuit Shorted
P0449 Evaporative Emission Control System Vent Valve/Solenoid Circuit Malfunction
P0450 Evaporative Emission Control System Pressure Sensor Malfunction
P0451 Evaporative Emission Control System Pressure Sensor Range/Performance
P0452 Evaporative Emission Control System Pressure Sensor Low Input
P0453 Evaporative Emission Control System Pressure Sensor High Input
P0454 Evaporative Emission Control System Pressure Sensor Intermittent
P0455 Evaporative Emission Control System Leak Detected (gross leak)

The fourth from the end indicates a "Low Input" to the sensor; this could be as simple as a dirty connector on the wires that connect to the sensor.
Find the sensor, and dis-connect/re-connect several times; this often re-establishes good connection.
Sorry, I don't know the location of the sensor.

The only thing you can do is check your gas cap, ...The rubber sealing ring on the gas cap can become distorted or nicked with age and abuse.
Solution is to replace the cap; not too expensive.

Another thread poster today indicates he has a gas tank that leaks when it's filled.
Mebbe fill up yours, and see if you get liquid gasoline dribbling from a rusted-out spot in the roof of the gas tank, or from a bad seal at the ful pump clamp ring.
As far as the PCM is concerned, a leak at the tank is the same as a leaking gas cap or underhood tube.

Good luck,
-Rick

[greengrandam84]

about month ago i went on a road trip and topped it off and gas started leaking out from the top of the tank. ......?!?!?!?

[rixGAphx]

Several possibilities:
* Rusted-thru hole.
* Bad sealing ring and/or oring, at top of fuel pump.
Much less likely IMO, but possible.
* Loose fuel tube clamp.
* Loose fuel filler line.

In any case, it is apparent that that is your leak location. :(
* Step one is to use as much gas as possible, since you cannot siphon or otherwise drain the tank (well, you COULD rig a line from your fuel filter outlet, and transfer your gasoline, via your in-tank pump, to a large container or another car's tank; IMO, not worth the trouble).
The dry tank and pump weigh about 30 pounds; gas weighs about 6.2 pounds per gallon IIRC, so 10 gallons = an additional 62 pounds that you don't want to wrestle if you don't have to.
* Step two is to drop the fuel tank, since there is absolutely no other way to access anything up there for inspection.
* Step three: Find the leak.
Report here if you want our thoughts.
* Four: Repair the leak, or replace the defective component.
* Five: Reinstall the tank.

Good luck,
-Rick

edit - PS:
I just re-read your post.
If you had truly 'topped-off', then you might have had a little gasoline in the filler tube, between the top of the tank and the filler car.
The filler tube is metal, but has a clamps-and-rubber-sleeve connection to the tank.
This connection is accessible if you crawl under the car (after jacking and supporting it) and reach-up/look for it.
If you're removing the tank, this is the first thing to loosen/disconnect.
One of the clamps might be loose or rusted-thru, allowing a continuous vapor leak; but only allowing liquid gas to leak if the tube has liquid in it (from 'topping-off').

So I would definitely inspect this clamping arrangement before dropping the tank.

Especially if somebody had ever dropped the tank to replace the fuel pump; they might not have re-tightened that clamp properly :eek:

[Nighthawk243]

Well... then you better start looking for a new tank then... (Unless your fuel connections are not put together well.)

[greengrandam84]

well about a yr ago, my father and I dropped the tank and installed a whole new fuel pump assembly b/c someone had put cigarettes in the tank when the previous owner had it. and the fuel pump clogged up on me while I was 1/2 way to NC from MD and had to have the car towed the rest of the way to my parented house..... that nicotine/tobacco is nasty stuff. anyway, i will try to look under there this weekend. until then im gonna try what....BPBAIR said and just clear the code and keep the tank more than 1/4 full.

[greengrandam84]

ok i finally had time to scan it again and yea its a P0442 small EVAP LEAK.... So where shall I look first ?!?!?

[rixGAphx]

Originally posted by greengrandam84
ok i finally had time to scan it again and yea its a P0442 small EVAP LEAK.... So where shall I look first ?!?!? Two things are certain:
1. You have a small evap leak.
2. You had liquid gasoline dribbling when you topped-off.
To me, this SCREAMS that the leak (or at least A leak) is on the top portion of your tank.
I think this needs to be fixed immediately.

Based on what I've read here and my own experience with replacing the fuel filter and fuel pump, I would:
1. Visually-check the rubber-and-clamp connection from the filler neck to the tank.
I would fill the tank, and VERY CAREFULLY see if that connection is leaking.

2. If no leak was visible with tank in place, then I would consume that tankful of gas during the next week or two.
I would locate a sound replacement tank, in case that became necessary.
Then spend a Sat morning dropping the tank and finding the leak.

Hope this helps,
-Rick