2007 Pacifica P0456 code
 

Engine light on, read code 0456: small fuel system air leak. I looked under car & in engine compartment, no bad hoses or connections. I've cleared the code 4 times & it returns in a few days. Gas cap looked fine. Took it to dealer, they ran a smoke check and could not find a leak or repeat the failure, they did see the code. Has anyone tackled this? I have read that a couple of owners have fixed it by replacing the canister purge valve. I may try this but any suggestions or experience out there?

indept,

Usually, the set condition for P0456 is a fluctuation in temperature. As the temperatures change, a vacuum is created in the fuel tank and evaporative system. The powertrain control module (PCM) monitors the evaporative system integrity monitor switch (ESIM). This switch is supposed to close within a certain calibrated time and if it doesn't the PCM will pick up the error and set the code.
You'll get a MIL light on if this happens at least 3 times.
Now there are several things to check, sounds like your dealer has gone through the diagnostic procedure thoroughly.
In some cases, the pin to terminal contact in the ESIM switch and PCM aren't adequate. That could be one thing to check, sometimes a new ESIM switch is needed.
Continue working with your dealer, I'm confident they'll get to the bottom of things!

Go to another dealer.

My question would be that it never happened before with a temperature change so why now, something must be bad. The dealer hasn't given me any confidence, just took my money.

But that would only mean paying another dealer to find nothing. Do you know of any common issues with this year Pac? I remember reading about a fuel pump fitting cracking and causing this, is that a known problem or is it rare?

indept

That's a good question.
Although I can only make suggestions, it may not necessarily be these components at fault.
If there is any hesitation with your dealer, perhaps a second opinion with another dealer may be appropriate in this case.

The fault code you reference is for a small evap leak. Visually and physically Inspect the entire Evaporative Emission System for any of the following conditions:

Holes or cracks
Loose seal points
Incorrect routing of hoses and tubes
Loose or missing Fuel Filler Cap or seal
Damaged locking tabs on the Fuel Filler Cap and/or filler tube
Damaged seal points on the Fuel Filler Cap and/or filler tube

Yes. The "pump" (sending unit) on the right side will likely be cracked or partially broken off at the vapor line that runs between the "pumps". I do quite a few of them. You have to drop the tank and modify the flange on new sending unit before you put it back together. Sorry, I don't have any pics, I keep meaning to take some.


There is also the occasional ESIM evap switch that gets knocked off the canister because of the way it's oriented. Pretty rare though.

test 123

I found this on my wife's Pacifica a few years ago. I fabricated my own connection to replace the broken one on the passenger side module. The leak is back, and I know it's the same thing, as I did not anticipate my repair lasting as long as it did.

I have been over the service manual, and I've spent many many hours on google and cannot find an answer to the following question- What is the purpose of this vapor line? It appears to be going just between the two in-tank modules. There's plenty of space in the tank to allow for air movement above the fuel level between the two modules. Why is this line even needed?

I know I can buy a new passenger side module and then use a flexible fuel line to make the connection, but would this be a problem?

Is there a reason I cannot simple PLUG the vapor line connection point in this situation? What problems could it cause? The rest of the EVAP system lines and devices are intact.

I've only got a few weeks to get her car ready for emissions.. this is the same time of the year that the problem first occurred (of course, just a few weeks before emissions were due for registration purposes :mad:)