Code P0456

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TalkeetnaDodge

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Hello. I recently acquired a well maintained 2012 Ram 1500 (5.7 Hemi) (91K) - a new type of vehicle for myself. Today I noticed a MIL light. Auto Zone checked and came back with a P 0456 code. I replaced the gascap. But reader was unkowledgeable on how to erase the code. Note: I haven't tried the battery (negative disconnect). This summer, I had driven the vehicle about 800 miles, no issues, starts ok, idles ok, accelerates ok , no vibrations, highway: 18-19 mpg; city 14-15. Yesterday, a winter tire changeover, a 120 mile trip, I filled the tank enroute - no light. Today in the city : the MIL. Also , the light that advises ECN doesn't illuminate, the avg gas mileage (numeric) readout is not consistent, however, (the seem to indicate the correct fuel flow per the appropriate condition). I have been reading previous posts and understand that the there could be numerous issues with in the evaporative system and it seems that the best method to troubleshoot is via a smoke test. My OBD is in another car miles away.

Before throwing parts at it via a shop, I wanted to ask if this type of Code can be reset via a battery disconnect and if not, can that only be done with a Dodge shop tool? Any comments will be appreciated.
 

GTyankee

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p0456,
usually put the Gas Cap at the top of the list

The Purge Valve should be at the top of the list
it is under the hood, close to the throttle body

often a aftermarket fuel cap, will not work in a Ram truck
 
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TalkeetnaDodge

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As a 'newbie' to this vehicle, thanks. I stopped by another auto store and watched the clerk 'erase' the code on the OBD, but this action didn't extinguish the light. I will try the battery disconnect when the rain stops. I stopped by the Dodge Ram Dealer to inquire. They will troubleshoot that code with a smoke/leak detector ($200) and look at the 'normal' replacement type items, etc. (The clerk estimated low probability
for bad cap (which they can check) or poor gas. NOTE: Not so easy to DIY in AK in winter. A month to get an appointment. Fustrating not to be able to extinguish this type of code to see if transient or a 'loose' cap, when everything seems to run OK, otherwise.

Does anyone know, does the P 0456 affect fuel mileage (if just a tiny leak)? And how does the MIL light on affect the Economy mode readout.
 

Daw14

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Give it some time ,it should go out after a certain amount of drive cycles.
 
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TalkeetnaDodge

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I am inclined to think that since I had fueled and then MIL illuminated the next day that it was a gas cap issue. I find it curious as to why it's troublesome to extinguish the light for the code 0456 and if there is some relation between whatever is going on and fuel economy (is economy mode also disabled or just the indicator). I haven't driven enough to be able to tell a difference.
 

Daw14

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It’s been my experience,when a code is thrown my eco would no longer function.
 
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TalkeetnaDodge

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So far continuuing my education; having learned about evap system, fuel cap and tank design, MIL & ECo illumination. Disconnected the battery, one hr. during lunch, the MIL extinguished. ECO light and other MPG readings back to normal. Ordered an OBD so I don't have to go to Napa, Autozone, or O Reilley's (all helpful). Now wait and see if light comes back.
 

David H

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since I had fueled and then MIL illuminated the next day
Something about over filling at fuel stops comes to mind. Seem to remember something about people experiencing these issues after topping off the tank (to excess).
Maybe someone can elaborate on this?
 
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