Question about 2002 Ford Expedition

2 Answers

My check engine light comes on. took it to a parts store and the problem was either a faulty gas cap or something in the fuel system dealing with it pulling a vaccuum. sometimes when i pull the gas cap, there is definitly a vaccuum, other timesd there is not. sometimes the light goes out, sometimes it stays on. i know the gas cap is good, what else causes the system not to pull a vaccuum?

Posted by on

  • Marvin
    Marvin Aug 06, 2010




2 Answers

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 10 achievements.


    An expert that got 5 achievements.


    An expert whose answer got voted for 500 times.

  • Master
  • 1,857 Answers

You have a vent solenoid and a purge solenoid and a gas tank pressure sensor and a charcoal cannister, you also have vacuum lines, fuel cap, filler neck and the fuel pump seal itself which can all have a small leak.

So what a shop would do is apply a slight bit of pressure using a smoke machine so as to see where smoke leaks out. Also they would check the other parts for proper function. If everything checks out then in some cases a reprogram for the computer is the only fix.

Posted on Aug 07, 2010

  • Level 2:

    An expert who has achieved level 2 by getting 100 points


    An expert that got 5 achievements.


    An expert whose answer got voted for 20 times.


    An expert who has answered 20 questions.

  • Expert
  • 135 Answers


Posted on Aug 06, 2010


1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi there,
Save hours of searching online or wasting money on unnecessary repairs by talking to a 6YA Expert who can help you resolve this issue over the phone in a minute or two.

Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.

Here's a link to this great service

Good luck!

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

I have a 2005 gmc yukon with gas fumes coming from fill tube area. No visible leaking.

you open the fill door and you smell gas?

is the check engine light on?

is the filler tube rusted?

have you tried a new fuel cap from the GM deal (do not use aftermarket caps from your local parts store)?

I’m happy to assist further over the phone at

Apr 02, 2013 | 2005 GMC Yukon

1 Answer

Check engine light came on and code said to replace gas cap, did that and two weeks later check engine came on same code, then one day fuel light came on and gauge went to fueull then empty 2 times , now...

You wouldn't think a gas cap would be that important, but it is. When it's loose or cracked, fuel vapors leak out and can throw the whole fuel system off. This causes a reduction in gas mileage and increases emissions.
What causes it: If you get an error pointing to the gas cap it means fuel vapors are leaking out of your cap. This means the cap is either cracked or just wasn't tightened well enough.
What you should do: If your car isn't feeling jerky or strange when the check engine light comes on the first you should check is the gas cap. Pull over, retighten it, and take a look at the cap to see if it has any cracks in it. Continue driving and see if the check engine light turns off. Alternately, you can purchase a gas cap for about $3 at an auto parts store. All you need to do is take the old one off and screw on the new one. If you've already made it to the store, you might as well just replace it. While not car-threatening, it's good to take care of this right away to improve gas mileage.

Aug 11, 2017 | 2004 Chrysler Pacifica

2 Answers

I have a 2001 pontiac gran prix gt, recently the gas cap was left off and the service engine light came on. i read somewhere that this light will come on when cap has a leak or is left off? I took the car...

If the cap was left off and then the light came on, I'm sure that you already have, put the cap back on and then have them clear the codes. If it returns then we can move forward with spending money and replacing parts. Let me know.

May 17, 2011 | 2001 Pontiac Grand Am SE

3 Answers

My check engine light came on code P0446; dashboard says "check gas cap" i took it off retightened it and check engine light still on. I noticed that the metal flap for the gas nozzle is...

The metal flap should not trigger the sensor. Once you tighten the gas cap you should clear the code and see if it comes back. Otherwise it will take a while to go away.
If it does come back even though the gas cap is tight it could be the rubber seal around the gas cap replacing that can sometimes fix this issue also.

May 04, 2011 | 2008 Jeep Grand Cherokee

1 Answer

2006 Saturn Relay Check Engine Light

PO455 is a large evaporative fuel leak. A bad fuel cap is ONE of the things that COULD be the problem. Fuel system cleaning only lightened your wallet. Reading your post is confusing. Did all this start AFTER the Valvoline Wallet Flushing? If so , they left something loose or disconnected. I would find a qualified repair shop to fix the problem, and if it has anything to do with what Valvoline did, make them pay the bill.

Nov 12, 2009 | 2006 Saturn Relay

1 Answer

Check Engine light goes on consistently

I would take the car to an autoparts store and have them scan the computer for codes stored. Most parts stores will do the scan for free. The check engine light is to alert you that the computer has noted a fault in one of the car's systems. A loose or faulty gas cap can cause an intermittent check engine light, but it could also be something in the evaporative emissions system that is causing it. Getting the codes should help end speculation so that the problem may be properly addressed. Sorry for your trouble and I hope this helped. Best wishes.

Sep 16, 2009 | 2009 Toyota Camry Hybrid

1 Answer

My check engine light came on on the right side, and then my fuel gage went bonkers. I was in park and the fuel gage went to empty. I turned off and then it took awhile to come back up to full. I filled up...

I hope you did not top it off because filing it up like that will wreck havoc on the evap system. The engine light should go away as the gas in your tank is used up, or it may take some time, but hopefully it goes away. Just next time you fill up don't top off when it clicks off thats it. Also make sure the gas cap is tight. A loose gas cap can make the check engine light come on. I am an emmission repair specialist, and deals with these crazy things sometimes lol.

Aug 12, 2009 | 2004 Oldsmobile Alero

1 Answer

I am getting a tighten gas cap message, however cap is on and tight. Check engine light is on

The gas cap is most likely faulty. The gas cap is an integral part of the evaporative emission system. If it is not sealing or venting properly, it can affect the proper operation of this system. I would replace the gas cap and have the check engine light reset at an autoparts store. Most stores will scan/reset computer for free. Hope this helped and best wishes.

Aug 07, 2009 | 2007 Chevrolet Impala LS Sedan New Cars

1 Answer

Check engine light comes on, gauges light comes on

What sensors did you replace? It sounds like a problem that could be caused by something in the evaporative emission system, like a faulty purge solenoid or evap cannister problem. Does the tank take fuel slowly when filling up? You could also have a faulty gas cap. That is the first thing I would look at. It is an integral part of the evap system. Hope this helps and best wishes.

Jul 23, 2009 | 1990 Plymouth Voyager

4 Answers

Service engine light on 2003 infinity g35

The quickest way to determine the cause is to visit a local parts store, of a major chain such as Autozone, etc. most of these offer a free computer scan that will reveal the source of the engine light. In the mean time, try refueling with a full tank of fresh fuel from a different source than you used the last time. sometimes water or other fuel problems can cause the light to come on.

And yes the loose fuel cap may cause the light. If you have more than 60,000 miles on your car, it may require some tune up parts such as oxygen sensors and such. CHECK YOUR WARRANTY!!! most states require the manufacturer to replace the emission related parts at mileages of 100,000 or even 150,000 so dont buy something you could get for free!

Jan 04, 2009 | 2005 Infiniti G35

Not finding what you are looking for?
2002 Ford Expedition Logo

148 people viewed this question

Ask a Question

Usually answered in minutes!

Top Ford Experts


Level 3 Expert

81400 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22359 Answers

gerry bissi

Level 3 Expert

4376 Answers

Are you a Ford Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides