How I Fixed My Code P0456
Posted: Sat Dec 31, 2016 2:30 am
Re: Check engine light on due to code P0456 (small evaporative system leak detected). All of this information applies to a 2008 PW, but the theory should apply to any vehicle (sometimes they change the name of system components from year to year).
It's been a couple months since my check engine light first came on because of this code. When I read what it was on my scanner, I cleared the code and checked my gas cap for tightness and forgot about it since it was nothing serious. But then it started repeating the same code every week or two, so I figured I better get to the bottom of it.
The most common failure is a bad rubber seal on the gas cap, even though I couldn't see any cracks or deformities, I decided to replace it since it was the original eight year old cap. I got an O.E. Mopar replacement, cleared the code again and waited to see if it would come back on. Sure enough, after a few more trips to work, the CEL popped back on with the same code.
Next on my diagnostic list was to carefully check all of the rubber and plastic lines in the evaporative system for cracks, splits or loose connections. I started at the evap/charcoal canisters mounted just in front of my fuel tank and followed each line to and from the canisters throughout the entire system. The hardest ones to check are on top of the fuel tank, but a good flashlight and mirror can help with those. I didn't find any problems with the lines, so now it was time to focus on components.
The first and most obvious component is the canister. It's pretty well protected between the frame rails, but you never know when a stray stone or piece of road debris may get kicked up there and damage something. Mine looked good with no signs of splits or cracks.
Every evap system has a vent/inlet somewhere, mine is above the transmission bell housing.
The cap is just an open restrictor to stop debris or bugs, like mud dobbers, from building a nest and plugging the vent line.
The next component inline is the filter, this is to stop any dust from entering the evaporative system. It's a mini air filter inside a plastic housing.
The next component is called the "Evaporative System Integrity Monitor" (ESIM for short). It locks on to the canister. This is a double weighted check valve that allows pressure venting or vacuum relief at predetermined pressures based on the weight of the check valves.
To remove the ESIM, lift up the locking tab and rotate it 45º clockwise.
There's an o-ring under the ESIM, make sure it doesn't get lost and check it's condition.
The ESIM is glued together and is supposed to be non serviceable 
. Looking inside the ESIM you can see that a layer of superfine dust made it past the filter media and took up residence on the check valve causing it not to seal.
My solution was to spray aerosol brake cleaner into the ESIM, shake it around and then quickly blow it out with compressed air. I did this two or three times until it looked clean. Make sure not to let the chemical sit for too long as it will ruin the rubber check valve (spray it in, shake and blow it out). The ESIM is available to purchase as an individual part for $30-40, but why buy it if you can clean it.
The next thing I did was blow out the vent filter and lines (a rather impressive cloud of dust). In fact it wouldn't be a bad idea to make this an annual maintenance item if your truck spends a lot of time off road or in dusty conditions.
It's been a couple weeks since I did all this work and so far no check engine light and no pending codes. If this hadn't fixed it, other components to check would include the purge solenoid valve (under the hood), fuel fill neck and hoses, fuel pump/sending unit & o-ring and finally the fuel tank.
After seven years of government work in the desert, the dust finally took its toll. Luckily I was able to find it and fix it with the investment of a little time and effort. I hope this will help someone else that may be experiencing the same problem and help save some money and a trip to the dealer/shop.
Happy New Year!!!
It's been a couple months since my check engine light first came on because of this code. When I read what it was on my scanner, I cleared the code and checked my gas cap for tightness and forgot about it since it was nothing serious. But then it started repeating the same code every week or two, so I figured I better get to the bottom of it.
The most common failure is a bad rubber seal on the gas cap, even though I couldn't see any cracks or deformities, I decided to replace it since it was the original eight year old cap. I got an O.E. Mopar replacement, cleared the code again and waited to see if it would come back on. Sure enough, after a few more trips to work, the CEL popped back on with the same code.
Next on my diagnostic list was to carefully check all of the rubber and plastic lines in the evaporative system for cracks, splits or loose connections. I started at the evap/charcoal canisters mounted just in front of my fuel tank and followed each line to and from the canisters throughout the entire system. The hardest ones to check are on top of the fuel tank, but a good flashlight and mirror can help with those. I didn't find any problems with the lines, so now it was time to focus on components.
The first and most obvious component is the canister. It's pretty well protected between the frame rails, but you never know when a stray stone or piece of road debris may get kicked up there and damage something. Mine looked good with no signs of splits or cracks.
Every evap system has a vent/inlet somewhere, mine is above the transmission bell housing.
- If pressure needs to be vented or air needs to be drawn in, this is where it happens.
The next component inline is the filter, this is to stop any dust from entering the evaporative system. It's a mini air filter inside a plastic housing.
- My filter sits on top of the evap/charcoal canister assembly.
- The ESIM is the bad boy that will turn on your check engine light if it sees that pressure/vacuum isn't being maintained in the system. It's a leak detector, that's what the two wires are for.
. Looking inside the ESIM you can see that a layer of superfine dust made it past the filter media and took up residence on the check valve causing it not to seal.The next thing I did was blow out the vent filter and lines (a rather impressive cloud of dust). In fact it wouldn't be a bad idea to make this an annual maintenance item if your truck spends a lot of time off road or in dusty conditions.
- Blowing out the vent line.
After seven years of government work in the desert, the dust finally took its toll. Luckily I was able to find it and fix it with the investment of a little time and effort. I hope this will help someone else that may be experiencing the same problem and help save some money and a trip to the dealer/shop.
Happy New Year!!!
( This might be a challenge.)
Thats the OLD MIMITW. You got to update ! 
I cut the bad section out, and used a fuel line hose and 2 hose clamps. Had a critter chewing on the line at my stepson's place up in Bailey Co.