P0456 Evap Small Leak Code (Solved)

[Bigfoot-NM]

Just thought I would share what I went through and what actually solved a pesky P0456 Evap Small Leak I was getting on my 2006 X with 4.0L engine.

For information, according to the manual, the test for the evap system will only run on a cold start and only if the fuel tank is somewhere between 3/4 and 1/4 full.

I was intermittently getting a check engine light with the dreaded P0456 code. It would only happen when my gas tank was somewhere between 1/2 and 1/4 tank full.

First thing I tried was replacing the gas cap with a Mopar gas cap. It didn't fix the problem.

Next, I bought a smoke tester and smoked it three separate times, not finding any leaks. I would hook the smoke tester up at the vacuum line at the purge solenoid in the engine compartment. I also hooked up the smoke tester back at the evap canister located in the right rear wheel well. There was never any leaks in the system and the system would pressurize up fine with the smoke tester.

I visually inspected all the vacuum lines from the engine bay, all the way along the frame, on top of the fuel tank, and around the Evap Cannister. Nothing, everything looked good.

Out of frustration, I finally decided just to replace the Natural Vacuum Leak Detection Pump (NVLD).

I'm happy to report that two months later and the Evap system has been working properly and have not had any check engine light.

 

[Daryl]

Thanks for taking the time to share. I’m certain it will help someone in the future.

 

[Vcook]

holy shit, this is me. same code. Mine happens when i'm between 1/2-3/4 tank. I repalced the cap. I smoked the system, nothing.

I'm looking into this Natural Vacuum Leak Detection Pump (NVLD) right now. Thanks!!!

 

[JMT]

Just thought I would share what I went through and what actually solved a pesky P0456 Evap Small Leak I was getting on my 2006 X with 4.0L engine.

For information, according to the manual, the test for the evap system will only run on a cold start and only if the fuel tank is somewhere between 3/4 and 1/4 full.

I was intermittently getting a check engine light with the dreaded P0456 code. It would only happen when my gas tank was somewhere between 1/2 and 1/4 tank full.

First thing I tried was replacing the gas cap with a Mopar gas cap. It didn't fix the problem.

Next, I bought a smoke tester and smoked it three separate times, not finding any leaks. I would hook the smoke tester up at the vacuum line at the purge solenoid in the engine compartment. I also hooked up the smoke tester back at the evap canister located in the right rear wheel well. There was never any leaks in the system and the system would pressurize up fine with the smoke tester.

I visually inspected all the vacuum lines from the engine bay, all the way along the frame, on top of the fuel tank, and around the Evap Cannister. Nothing, everything looked good.

Out of frustration, I finally decided just to replace the Natural Vacuum Leak Detection Pump (NVLD).

I'm happy to report that two months later and the Evap system has been working properly and have not had any check engine light.

Thanks. This may work for me

 

[John Scoggins]

The LVDP can be tested with a balloon, vacuum source and 12V source if you want, google it and you can see it is not to hard, might save you some money, or confirm the problem is with the LVDP.

 

[Kayakwb]

Where did you find the part?

 

[Bigfoot-NM]

Where did you find the part?

I think it was a Dorman or Crown part and I got it on

Where did you find the part?

I got the Dorman 310-500 at a local auto parts store.....I think Advanced Auto Parts. This part is for a 2006 TJ>

 

[Jorge Bolivar]

For the 2004 models, the Dorman part number is 310-260.

 

[OFFRD TJ]

Any ideas where the Natural Vacuum Leak Detection Pump is located on a 2006 TJ? I am having the same issue with a P0456 code. I replaced the gas cap but doesn't look like it fixed the issue. Thanks!

 

[Bigfoot-NM]

Any ideas where the Natural Vacuum Leak Detection Pump is located on a 2006 TJ? I am having the same issue with a P0456 code. I replaced the gas cap but doesn't look like it fixed the issue. Thanks!

Right rear fender well behind the tire

 

[Jorge Bolivar]

Any ideas where the Natural Vacuum Leak Detection Pump is located on a 2006 TJ? I am having the same issue with a P0456 code. I replaced the gas cap but doesn't look like it fixed the issue. Thanks!

See the embedded pic for LDP location guidance.
In the 2004 TJ Service manual page, 25-14 PDF document page1684 the Leak Detection Pump is discussed in detail.

I hope this helps.

 

[CasonsTJ01]

If I may ask. I have been chasing this P0456 code for like 3 months. I have an 04 manual with the 4.0 I have replaced the Fuel tank, Fuel sender unit and pump. LDP, canister, vent valve, purge valve, and the evap lines on the tank. I even put on a new gas cap. this problem is so odd. I have the rubber pieces that connect to the intake manifold on the way. Now The code clears itself when the tank level is below 1/4 full. and comes back about 3 days after I fill up. It wont go away until its below a 1/4 tank. I have smoke tested everything and I cant find anything. Even smoke tested when it was at 3/4 and 2/4 full. and nothing is showing a leak. Does anyone have any ideas about this? I'm literally out of ideas.