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P0457 "loose fuel cap" error code


FadeToGray

TJ Enthusiast
Joined
Feb 4, 2019
Messages
173
Location
NH
I’m getting a P0457 error (loose gas cap) on my 2005 LJ.

I’ve replaced the gas cap with an OEM Mopar one but that didn’t help.

Any other things I could try before bringing it to my local shop that don’t require dropping the tank?

Thank you

A58F1D1F-1143-4E42-A06D-943BB65F574C.jpeg
 

Chris

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Sep 28, 2015
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Florence, Arizona
Often times this is a leak in the evap system. The best way to find it (since it can usually be very hard to spot little leaks with the naked eye) is a smoke machine.
 
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Jerry Bransford

TJ Guru Moderator
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Nov 9, 2015
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Escondido California
You may not have enough start cycles to clear the code. Have you cleared the code with the reader? If you have and it comes back it's probably a cracked hose or fitting below the filler cap like one of the various hoses or connectors around the gas tank.
 

Cisco Kid

Been around the block...twice!
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May 28, 2017
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Texas City, TX 77590, United States
I had a Dodge Dakota that did that. After several gas caps I took them all to the shop. the checked it and they smoked it and could not fix it. No leaks.
What I did to stop the problem...Took the original Cap and tightened it but stopped before it clicked. Problem solved. Not a problem for two years.
Just tighten it and stop before it clicks. If it clicks then remove the cap and re-tighten it with a little less pressure.
 
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FadeToGray

FadeToGray

TJ Enthusiast
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Feb 4, 2019
Messages
173
Location
NH
So do I run the smoke machine along the Evap line and if there is vapor I’d see it in the smoke? Not sure I understand what to do with the smoke machine?
 

bromel

TJ Enthusiast
Joined
Oct 11, 2018
Messages
480
Location
Montauk, NY
I had the same code, and I too bought the mopar cap with no success. Strangely, the Stant gas cap from Amazon fixed the problem entirely.
 
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FadeToGray

FadeToGray

TJ Enthusiast
Joined
Feb 4, 2019
Messages
173
Location
NH
I had the same code, and I too bought the mopar cap with no success. Strangely, the Stant gas cap from Amazon fixed the problem entirely.
Maybe I’ll buy one and try it for the $10 it will cost.
 

KCsTJ

TJ student
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Jan 9, 2018
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Location
Farmersville, TX, United States
Here's a DIY smoke machine. It's a HF hand transfer pump for <$10.
Attach it to the intake as shown. Stuff a rag in the exhaust pipe and stopper the throttle body intake.
Light the cigar and pump smoke in and watch for it to show smoke somewhere.
20190309_143512.jpg

Works the same on a 2.5L or 4.0L.