Gas Cap Light -

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Gas Cap Light


Old 04-30-2008, 11:58 PM
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Default Gas Cap Light

Anyone out there ever get a gas cap warning come on in their truck. I have on 08 1500, and today the warning came on, I unscrewed the cap and nothing. I turned the truck off and unscrewed the cap and put it back on, started the truck and the warning was still there. Anyone know what the deal is. Dont tell me I have to go to the dealership to have them turn it off, cause that sucks at $4.00 a gal. Thanks for any help you can give me.
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Old 05-01-2008, 01:29 AM
07 Ram TRX4
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Default RE: Gas Cap Light

"Gas Cap" light? I've never heard of one... Sure you are not just running out of gas?
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Old 05-01-2008, 01:34 AM
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Default RE: Gas Cap Light

plenty of gas. The message appears on the instrument panel, same place where it tells you your door is open or change your oil
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Old 05-01-2008, 10:27 AM
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Default RE: Gas Cap Light

You can get a code reader to turn the lamp off. I've read it'll go away by itself in a day or so. Mine threw the code once. I had not tightened the cap, so it complained. I used my code reader to erase the code.
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Old 05-01-2008, 11:50 AM
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Default RE: Gas Cap Light

I don't know about a gas cap light (my mother-in-law's explorer has one though.) I just played the game with my 02 Ram with the check engine light coming on throwing the evap code, after having the code cleared at at autozone I tightened the gas cap and prayed. No luck, a few days later it came back on.

Long story short after paying the dealer $120 and sitting in their waiting room for two afternoons, they found that the gas cap was bad and that I had a hose that was cracked all to hell. I hate that evap system...what a waste of time and money.
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Old 05-01-2008, 06:36 PM
Foiled is offline
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Default RE: Gas Cap Light

This is new. They added this because people was getting check engine lights because of the loose or missing caps. So they added a gas cap light so people know what it is.

Read the manual and see if it has special instructions about this light, if that does not work then I would it in. If the cap is on and the light is still on then there may be a problem with your tank.
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Old 05-02-2008, 09:32 PM
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Default RE: Gas Cap Light

yea i have that error, i'm not sure why its on, i've had it on for two weeks now, i've gotten many fuel ups and it hasnt come off, i plugged it into an OBDii senor and it comes up as a leaking vaccume line, thats probably what yours is, i just deleted the error, lol i dont know if that was the best decison but its what i chose
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Old 05-02-2008, 10:02 PM
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Default RE: Gas Cap Light

Fuel cap loose P0457. Your truck has a evap leak detection sytem that the pcm monitors the fuel tank for leaks OVERNIGHT. This is called natural vacuum. When the tank is hot it expands and when it cools the tanks will "suck" in and close the switch on the ESIM. The pcm knows that the night before it had no leak, Then next night it seen a different fuel level and now it has a leak and it assums that you left the cap off. Put the cap on and it should go off the next day or two. Make sure you don't make a short trip as it will not justify the pcm to monitor the evap system. I have had some rental cars come in with that code and found they have jumped railraod tracks and cut evap hoses with the suspension. Hope this helps!
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