Jeep Garage  - Jeep Forum

Jeep Garage - Jeep Forum (http://www.jeepgarage.org/forums.php)
-   Troubleshooting/Problems (http://www.jeepgarage.org/f181/)
-   -   Check Engine - Code P0456 (http://www.jeepgarage.org/f181/check-engine-code-p0456-43130.html)

RustyAxeCamp 06-08-2012 05:16 PM

Check Engine - Code P0456
 
Did the turn key code check and got P0456.

Gas cap might have been loose..

That it? Tighten it and drive for a while and the light should go off?

When do I take her to the Dr?

jeepgcoman 06-08-2012 08:43 PM

Re: Check Engine - Code P0456
 
From the FSM:

P0456-EVAP PURGE SYSTEM SMALL LEAK

Theory of Operation
The theory behind the Natural Vacuum Leak Detection (NVLD) is adherence to the Ideal Gas Law. Pressure in a

sealed vessel will change linearly as a function of the temperature of the gas in the vessel. Even small leaks will
allow the pressure in the vessel to come to equilibrium with the atmospheric pressure. After key-off and a calibrated
amount of time, cool down from operating temperatures or diurnal ambient temperature the system pressure will
force the system to go negative or draw a vacuum if there is no leak. When the vacuum level reaches 1” H2O (0.25
KPA) the NVLD vacuum switch closes. This sends a signal to the NGC freezing a timer and registering a pass. If
a switch closure is not detected an assessment of leak size will be made.



When Monitored:
Ignition off. Fuel Level less than 88%. Ambient Temperature between 4C and 43C (39F and 109F) Close

Loop fuel system.


Set Condition:
Due to temperature changes, a vacuum is created in the fuel tank and EVAP system. With the EVAP system

sealed, the PCM monitors the NVLD switch. If the NVLD switch does not close within a calibrated time allowance,
an error is detected by the PCM. One Trip Fault. Three good trips to turn off the MIL.
Possible Causes
EVAP PURGE SYSTEM LEAK

EVAP PURGE SOLENOID

You may also want to PM member, Walt, and see if he may be able to help you. He also lives in Midland.


RustyAxeCamp 06-08-2012 08:54 PM

Re: Check Engine - Code P0456
 
Quote:

Originally Posted by jeepgcoman (Post 640848)
You may also want to PM member, Walt, and see if he may be able to help you. He also lives in Midland.


He PMd me. Thanks guys!

DAVY27 06-08-2012 08:55 PM

Re: Check Engine - Code P0456
 
disc the neg terminal and then reconnect it. if the light comes back it might be the evap system.

2005JGC 06-09-2012 12:55 AM

seems 9 times out of 10 the thing that causes this code along with other evap leak codes us the esim switch mounted to the charcoal canister... Its a pretty cheap part and once you understand how it detaches its super easy to replace.

Sent from my SCH-I500 using Tapatalk 2

RustyAxeCamp 06-11-2012 11:12 AM

Re: Check Engine - Code P0456
 
light went off the next day. Code was still in there. I unhooked battery and reset today. Started engine and let run for 3-4 minutes. No codes. If it doesn't come back, figure it was the cap?

2005JGC 06-11-2012 02:39 PM

Re: Check Engine - Code P0456
 
evap codes will take a couple days to reset especially small leak, it requires a cold soak after a drive cycle to run the monitor so it likely wont come right back... but yes, if it doesnt come back it would be safe to assume it was the cap.

hoffmanestates 08-29-2012 04:43 PM

mine just popped up two days after emissions testing ...

Sent from my LG-P999 using Tapatalk 2

06grand 08-30-2012 06:21 AM

Re: Check Engine - Code P0456
 
Im having the same problem, my mechanic is finally stumped. Ive had the system smoked, checked and replaced the gas cap. However, I may be onto something after seeing someone mention the esim switch above. Googled ESIM switch and got this [PDF] Chrysler Evaporative Leak Detection Systems



Some pretty useful info if you still have problems.

hoffmanestates 08-30-2012 06:45 AM

ill look into it

Sent from my LG-P999 using Tapatalk 2


All times are GMT -5. The time now is 05:05 AM.

Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Copyright 2012 - JeepGarage.Org
The Jeep Grand Cherokee Owners Community