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Code P0456 EVAP leak from leak detection pump filter with smoke test

Tiny
IFYUSER
  • MEMBER
  • 2003 VOLKSWAGEN PASSAT
  • 2.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 160,000 MILES
They smoked tested the evap system and found a leak from the air filter from the leak detection pump. Is it supposed to be sealed, when car is off? Or is the pump bad, if it leaking through the filter? They couldn't find any other leaks with the smoke machine.
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Saturday, August 22nd, 2020 AT 12:14 AM

16 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
If it is leaking from the air filter then the purge valve is most likely leaking. This is what allows the vapor into the intake system so the engine can use it.

However, they need to make sure the valve is close when they are smoke testing it. Other wise they need to remove the feedline to the purge and plug it and then smoke test it.

In fact, here is the process to test this system from the manual. It sounds like to me that they may have not done it this way. By disconnecting each component as it says, they are separating the system so they can find where the leak is coming from.

Let me know if you have questions because this is one of the more confusing systems to try and diagnose. Most people just take a line loose and pump in smoke then replace anything that has smoke coming out and that is not always correct.

Lastly number 29 is the purge that I was talking about. It is located on the air filter housing.
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Saturday, August 22nd, 2020 AT 7:29 AM
Tiny
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I made a mistake.I meant the vent valve. The filter in the vent valve that's in the leak detection pump. Is it suppose to leak?
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Saturday, August 22nd, 2020 AT 3:51 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
If you are testing the entire system with smoke with the pump hooked up then yes, I would expect smoke to come out of there. The first step in that instructions that I sent was to disconnect the line from the pump to the fuel system and seal it then test the system. If it persists to move further into the system.
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Sunday, August 23rd, 2020 AT 6:33 PM
Tiny
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  • 51 POSTS
I found a small hose that was cracked at the vacuumed reservoir. I changed it and I notice now there's pressure when I remove the fuel cap. If there's pressure when I remove the fuel cap, does it mean the leak is gone?
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Thursday, August 27th, 2020 AT 6:59 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
That is a positive sign but not definitive. The EVAP system is meant to keep the fuel tank pressure at the proper level. However, the fuel tank could be sealed but there is a leak on the engine side of the EVAP system. If you found this line then I would simply drive the vehicle and if the light does not come back on then you fixed it.

Unfortunately time will tell but you have reason to be hopeful.
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Thursday, August 27th, 2020 AT 7:45 PM
Tiny
IFYUSER
  • MEMBER
  • 51 POSTS
I got the same code again. I bought a smoke machine and found no leaks on evap system or engine side. I removed the leak detection pump to bench press with a balloon. The balloon doesn't inflate that much. Is the ldp air pump bad? And will a bad ldp air pump cause p0442 or p456?
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Sunday, September 13th, 2020 AT 4:33 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Unfortunately both of these codes are pointing you to a leak and a weak pump would not cause this.

When you smoke tested the system, where did you put the smoke on the EVAP side?

I attached the testing. Let us know and we will figure this out. Thanks
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Sunday, September 13th, 2020 AT 8:04 PM
Tiny
IFYUSER
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  • 51 POSTS
I figured it out, you just find the rubber hose and cut it and replace. It was on top of the gas tank. But 16 feet of rubber hose fixes it.
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Wednesday, December 2nd, 2020 AT 9:11 AM
Tiny
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  • MECHANIC
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That is great and thanks for the update. Glad you got it solved and let us know what it was. Please come back to 2CarPros in the future. Thanks
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Thursday, December 3rd, 2020 AT 12:14 PM
Tiny
IFYUSER
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I figured it out. It's the EVAP pressure hose that goes to the leak detection pump. If not I can get a cut to size hose and replace the one that goes on top by just cutting it to length and feeding it through and using the connectors. Thanks
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Friday, December 4th, 2020 AT 10:45 PM
Tiny
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Awesome. Thanks for clarifying. Talk to you next time!
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+1
Saturday, December 5th, 2020 AT 12:42 PM
Tiny
JOSUé ULLOA
  • MEMBER
  • 5 POSTS
Hi, I have a Dodge Dakota 2002 and I have a code Evan leak small large leak, when I do the smoke test the only place where is coming from is the filter from the Evan leak detection pump, I don’t know what else to do I replaced the canister, the leak detection pump and the purge valve and I replace couple hoses form that area and still checking engine light come on, the fuel cap is new and the filler neck for the fuel is new, I can’t see on top of the fuel tank unless I take it down but I don’t see smoke form there. When I do the smoke test should I remove the hose from the filter vent valve and close it with a screw so then the smoke is not coming from there and hopefully comes for another place a hose on the fuel tank etc? Also, the purge valve has to connect Josie one’s says vac than other nothing so the vac one hose side should be connected to the hose that comes form the canister? Thanks
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Saturday, March 19th, 2022 AT 4:25 PM
Tiny
SQM
  • MECHANIC
  • 6,383 POSTS
Hello Josué Ulloa,

Since this issue is on a different make and model than the VW, please kindly open a new thread. This will put this in front of all the experts.
Simply ask the question by going to this link:

https://www.2carpros.com/questions/new

Thank you.
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Saturday, March 19th, 2022 AT 10:02 PM
Tiny
JOSUé ULLOA
  • MEMBER
  • 5 POSTS
Okay, thanks.
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Sunday, March 20th, 2022 AT 8:25 AM
Tiny
JOSUé ULLOA
  • MEMBER
  • 5 POSTS
It says an email for verification was sent click on the link to us to respond to your question but I'm not getting the email I checked the spam and nothing? Thanks
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Sunday, March 20th, 2022 AT 8:46 AM
Tiny
JETTABOYS
  • MEMBER
  • 4 POSTS
I have an 08 Jetta and I get the code p0455
And p0441. I fixed a leak from a hose connected to the secondary air pump seems to have helped my fuel trims I think. I smoked the system from the hose in Evap hose in the front and saw smoke come out of the right rear well. I took off the well cover and smoke was coming out of the leak detection pump filter with the car off. No other signs of smoke coming from anywhere else. Isn’t this system supposed to be closed off until activated?
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Tuesday, January 24th, 2023 AT 3:29 PM

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