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2005 mercury mountaineer check engine light on, gas cap, but keeps coming on

My check engine light came on, bought a new gas cap. Turn off the light and it comes back on once the gas gets to around a 1/4 tank of gas??

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Posted on Jan 02, 2017

  • 14 Answers

SOURCE: 2003 Mercury Sable gas cap light stays on!

make sure that the gas cap have a rubber gasket in it if it has accidentaly dropped off while you removed to fill the tnk it will not seal properly and create a vacum leak causing the ecm to turn on the light.

or did you have an accident or did you run over any thing that could have damaged the vapor canister at the bottom of the vehicle and if this is the case you will see the light on because a damaged canister can cause a vacum leak

Posted on Nov 11, 2008

  • 79141 Answers

SOURCE: abs light comes on


Posted on Feb 11, 2009

  • 202 Answers

SOURCE: In 97 mercury mountaineer, how to turn off "check engine" light

Go to the local parts store, have them check the codes (they will do this for free usually). It will tell you what sensor needs to be checked/replaced. Once the part is replaced, it will clear on its own. They can also reset the code, but it will come back if the trouble persists.

Posted on May 27, 2009

  • 65 Answers

SOURCE: I own a 2004 Mercury Mountaineer, and the ABS

On a Car like that you have little sensors on each one of the wheels. These sensors are small, delicate and finicky. You probably have a loose one or when the wheel heats up or reaches a certain speed, highway driving, it loses the connection and the light comes on.
The best way to fix this is go to a shop. Since the answer lies in the computer somewhere they need to check it. Note that the computer on your car stores the data when this happens and they should download the stored data if everything " seems fine ". Hope that helps

Posted on Jun 11, 2009

  • 94 Answers

SOURCE: 2004 Mercury Mountaineer fuel gauge not working

The most likely failure that will cause your problem is the fuel level sender in the gas tank. The sender will cause both the fuel gauge problem and the check engine light to be turned on. The sender will need to be replaced to repair the problem.

Posted on Jun 28, 2009

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What happens when the gas cap light in a 2008 Mercury Mountaineer comes on?

You check to see if the gas cap is loose

If that isn't the problem you diagnose the
Evap System after checking for OBD Codes

Sep 05, 2014 | 2008 Mercury Mountaineer

2 Answers

I just purchased a 03 Mercury Mountaineer, it only has 32000 miles on it yet it the computer keeps saying the gas cap needs to be looked at. i took it in and the service guy has said it may need a new...

vacuum hoses can also degrade with time and not just mileage. id have it smoked to find the leak. itll be a lot cheaper in the long run for you to do so.

Dec 05, 2017 | 2006 Mercury Mountaineer

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Check engine light

most likely, the gas cap isn't on tight enough. If air is allowed to leak in, it affects the emission control system, which triggers the check engine light.

Dec 02, 2013 | 2000 Mercury Mountaineer

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I got an P0442 emission control system leak (small leak) error code on my 2008 mountaineer. but it come gas capless....what could it be?

Not sure if you mean you do not have a gas cap or not. But if you do not have a gas cap, that is why you have the P0442 code and the check engine light on. The gas cap is part of the emissions system, it has to hold a vacuum. If it does not that is your "small Leak"...

Nov 13, 2010 | 2008 Mercury Mountaineer

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Mercury mountaineer check engine light help

No, just go to Autozone, they will pull codes for free.

May 30, 2010 | 2002 Mercury Mountaineer

1 Answer

2004 mountaineer code po 456 came up service engine light on. fuel cap replaced. still on.

the gas cap is the most common if u can reset code do so and if code comes back then need to check-- the fuel lines -purge valve and vent -also the canister--- for cracked disconnected damaged lines

May 09, 2010 | 2004 Mercury Mountaineer

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Gas Cap Error with Check Engine light

By "Replace the gas cap", do you mean put it back on, or buy another one? If you fuel these trucks with the engine running, or don't tighten the gas cap, the light will come on. It will also come on when the seal in your gas cap goes bad. I have had to replace the gas cap on my jeep and dodge already. It fixed the problem both times.

Jul 07, 2009 | 2007 Dodge Ram 1500 Quad Cab Sport

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