CAP LIGHT gone but throwing EVAP code.

Brian Keiper said:

It's funny because when you reset the codes the CEL goes off, but gas cap icon appears instantly.

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That happened to me at first. Now when I reset,.not only does the gas cap light go on immediately, so does the cel.

Been clearing codes consistently cel and gas cap light came on right away, 1/2 tank or less cel goes away and gas light stays on.

Pointing to what to fix i decided I will figure it out with time, honestly the truck runs fine I just read the codes to, make sure I'm not throwing anything else since my lights are already on.

Any more suggestions would be great

Brian, my experience and solution of this problem on my 03 and 07 is posted in the archives on this forum. Let me see if I can consolidate what I learned. Replacing the gas cap is always the first thing we do. BUT,,,some of the replacement caps are worse than the factory worn out cap. It is just the O ring that wears out and prevents an air tight seal. I agree with you the dealer is a last resort and I believe a poor choice. After throwing some easy to replace parts at this problem I learned that the most cost effective and accurate solution is to pressure test the system. My tech first did a deep scan. Using a professional diagnostic tool he looked at factory specs and compared them to operating run specs. From that he was able to determine what components need to be tested. He then did a pressure test. Bottom line the problem on my 03 was the fuel neck was leaking at the tank. Small leak, Unable to see but we could smell when in the garage closed up. That is not a fixable leak. Some people have used JB weld etc. I do not repair that way. A replacement tank from the dealer was $1000. My tech found a salvage replacement for $187. He tested and installed. Problem solved 2 yrs ago at 230K miles on the 03. On the 07 same steps but the problem turned out to be s bad purge valve and contaminated canister at 150k. My techs diagnostic time cost $100. The 03 parts and labor was right at $500. The 07 was just under $400. Hope this is helpful. Fitz

Brian Keiper said:

Been clearing codes consistently cel and gas cap light came on right away, 1/2 tank or less cel goes away and gas light stays on.

Pointing to what to fix i decided I will figure it out with time, honestly the truck runs fine I just read the codes to, make sure I'm not throwing anything else since my lights are already on.

Any more suggestions would be great

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All of your symptoms have gone down the precise path mine have. Chances are we have the exact same issue. Probably something with the fuel neck or the canister as I have replaced and inspected just about everything else. I don't smell gas, but I'm lifted and can't get my truck in an enclosed garage. Just like you stated, truck has been running fine for over a year like this. Might be possible I have lost some slight mpg, but I have done many mods to the vehicle that more than likely caused that.

If you haven't already go to rock auto, search for this for your truck (see photos). Replacement is less than $30 shipped. It's attached to the gas tank. Fixed my 11

Hey guys, I just experienced this problem with my '15 Sport. I had the fuel cap light then the CEL came on. Cleared the code and had the P0440, P0456, and P0457. Started to do some troubleshooting and replaced the fuel cap and the Purge valve (under the hood next to throttle body) and didn't change anything. Then after doing some more research and reading other forums I came across the Leak Detection Pump. Replaced the Leak Detection Pump and drove about 10 miles in 2 key cycles and the gas cap light went out. Drove about 50-60 miles shut the truck off for the night and the next morning my CEL light went out and haven't had an issue since. It's been about 3 weeks and I drove 1300 miles since the lights went out. Below is the link to the part. It's a $20 part and easy to replace. Mine sits at the rear of the fuel tank behind the heat shield. It is 1 electrical connector and then you pull on the little tab and twist then it comes out. I went to my local autozone and they had 1 in stock so it's worth a shot.


https://www.autozone.com/engine-man...+pump&fromString=search&isIgnoreVehicle=false

Alright, since a few of you have already suggested replacing the Fuel Vapor Leak Detection Pump I decided to throw one last part at it before paying to have it diagnosed. I had already replaced the gas cap and purge solenoid within the last year which are the other two most common fixes. I had thoroughly inspected all of my lines and deemed them good.

In the last year or so I have reset tunes and codes many times and noticed that when doing so more recently, the gas cap light and cel would come on right after I first turned the key on, not even getting out of my driveway. Whereas before it would take some driving before they would come back on. So, I put in the leak detection pump yesterday and cleared the codes. Turned the key over and the cel did not come on this time, but the gas cap light came on. I restarted the truck probably ten times and even let it run for 10 minutes or so a couple times and the gas cap light would not go off. Figured once I get to driving it around the cel would come back on.

Well, I came out this morning to move the truck out of the driveway and to my surprise, no gas light. I have a thread in here where I provided a chronology of events for well over a year. I was initially able to ward off this issue for a full year by placing some vaseline on the gas cap a couple times, but that stopped working eventually. I am not going to consider my issue resolved until I drive a full tank or two, but this is incredibly positive considering the cel and gas cap light would immediately return in the past after code resets. I do believe this has now fixed my issue. I'll provide an update here and hope to be closing out the issue in my other thread after I run some miles on the truck.

The leak detection pump was $24 after tax at AutoZone and took me 5 minutes to replace. @Brian Keiper. Considering your symptoms evolved in the exact same manner mine did, this might be worth a shot.

Thanks to the few of you that recommended giving this a try, much appreciated. On another note, when I removed the old pump and was sliding out from the truck, the pump had a rattle in it. I didn't remember the new pump having that rattle when I was installing it. I found the white part in the picture below moves back and forth when you tilt it. I could be wrong, but i don't think the new one did that.

They’re supposed to rattle, that white piece slides back and forth based on pressure/vacuum in the evap system.

Well, I'm considering myself fixed. Have run a tank of gas through the truck since replacing the Fuel Leak Detection Pump and gas cap and cels have not come back!

I had the same issue. Threw 3 codes last month. Replaced the gas cap, nothing. Replaced the purge valve. Nothing. I ended up replacing the Leak Detection Pump and it has fixed the issue. Was about 30 bucks from the dealer if I'm not mistaken.

DaddyGouge said:

I had the same issue. Threw 3 codes last month. Replaced the gas cap, nothing. Replaced the purge valve. Nothing. I ended up replacing the Leak Detection Pump and it has fixed the issue. Was about 30 bucks from the dealer if I'm not mistaken.

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Same story here. 3rd times the charm!

Thank you guys I'll be doing this when I get the time, I've been locked in remodeling my house and put the truck on the side burner for now, but thank you for the info and I will try the "LEAK DECTION PUMP and get back you guys.

Thank you

MarshRam said:

Same story here. 3rd times the charm!

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Marsh - I assume your lights have stayed off? I have a 15' with the same issue. CEL and gas cap lights on. Have replaced the purge valve, gas cap with OEM and lead detection pump. Then I had it checked by an independent shop where they pressure tested the system and everything reported as normal. They cleared the CEL but it came back on the 2nd time I started it up (P0456). Truck drives fine but I have a problem paying $500 a month with the dash all lit up like New Years eve... Didn't know if there was anything else I could check on my own before sucking it up and taking it to the dealer.

BlackRambo said:

Marsh - I assume your lights have stayed off? I have a 15' with the same issue. CEL and gas cap lights on. Have replaced the purge valve, gas cap with OEM and lead detection pump. Then I had it checked by an independent shop where they pressure tested the system and everything reported as normal. They cleared the CEL but it came back on the 2nd time I started it up (P0456). Truck drives fine but I have a problem paying $500 a month with the dash all lit up like New Years eve... Didn't know if there was anything else I could check on my own before sucking it up and taking it to the dealer.

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I’ve seen a few fuel pump housing cracked on the top and causing the evap leak. You’d need a smoke machine in order to find it though. There have also been PCM updates to fix a P0456 code as well.

BlackRambo said:

Marsh - I assume your lights have stayed off? I have a 15' with the same issue. CEL and gas cap lights on. Have replaced the purge valve, gas cap with OEM and lead detection pump. Then I had it checked by an independent shop where they pressure tested the system and everything reported as normal. They cleared the CEL but it came back on the 2nd time I started it up (P0456). Truck drives fine but I have a problem paying $500 a month with the dash all lit up like New Years eve... Didn't know if there was anything else I could check on my own before sucking it up and taking it to the dealer.

Click to expand...

BlackRambo said:

Marsh - I assume your lights have stayed off? I have a 15' with the same issue. CEL and gas cap lights on. Have replaced the purge valve, gas cap with OEM and lead detection pump. Then I had it checked by an independent shop where they pressure tested the system and everything reported as normal. They cleared the CEL but it came back on the 2nd time I started it up (P0456). Truck drives fine but I have a problem paying $500 a month with the dash all lit up like New Years eve... Didn't know if there was anything else I could check on my own before sucking it up and taking it to the dealer.

Click to expand...

Yep, that Leak Detection Pump was the issue. You've eliminated the most common problems, sorry to hear it didn't solve it. I know the feeling of making that payment all the while riding around with a cluster lit up like a christmas tree. Hope you find the culprit next round. Smoke test seems to be the next logical step.

Tach_tech said:

I’ve seen a few fuel pump housing cracked on the top and causing the evap leak. You’d need a smoke machine in order to find it though. There have also been PCM updates to fix a P0456 code as well.

Click to expand...

MarshRam said:

Yep, that Leak Detection Pump was the issue. You've eliminated the most common problems, sorry to hear it didn't solve it. I know the feeling of making that payment all the while riding around with a cluster lit up like a christmas tree. Hope you find the culprit next round. Smoke test seems to be the next logical step.

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Thanks guys. I'll see if I can't find a local shop to do a smoke test before anything else.

This seems to be an inherent problem with a lot of these. Mine is a 2016 and I am going thru all the same stuff you guys have. It seems like a lot of BS to put up with. I have subscribed. Please update with any improvments if you get them.

This thread was super helpful. I have a 2014 that threw a P0440 after I replaced the cap and got rid of the loose gas cap light. I replaced the Leak Detection pump and no more P0440! As a reference, I had no other codes. I had previously performed a system leak check and EVAP valve check... both passed.