Has a new cap on it. My son just bought the car and the light came on the very next day.
SOURCE: I Own 98 dodge Dakota check Engine light, code PO
No the flap inside the fuel filler pipe is just an anti theft device to make it more difficult to siphon fuel out of the tank. The most likely cause for the code it the fuel cap itself. If you don't get the gas cap tight after you fuel up, it can set a computer code and turn on the Check Engine Light. After you check to make sure the cap is on tight, clear the engine code and see if it comes back on. If it does then have the fuel cap tested to make sure that it doesn't have a vaccuum leak.
SOURCE: trouble code po456 evap small leak ? could it be the gas cap ?
Can't say 100% obviously, but quite often that is the cure, but try to take some time to make sure all your hoses , in the system are in good shape & tight.
SOURCE: we have a 2002 dodge durango that we bought used
A small evap leak is usually a vapor line with a small crack in it or fuel cap seal. The vapor lines usually crack where they meet a plastic or metal line attachment. Where the line has to swell a bit to fit the other line is where the small crack occurs. You can feel each line at these points and find the crack. It will feel smooth all the way around and then a rough spot. Check the lines going to the service port under the hood and then follow them back to the canister looking closely at each connection. If you don't find anything replace the fuel cap and retest. It is rarely any of the other system parts you mentioned. If it goes undetected long enough a new code will come up as P0442 medium evap leak, meaning the crack has become bigger and possibly easier to find. It is strictly emissions and will have no effect on the way the vehicle runs.
SOURCE: very small evap leak
inspect all the hoses in the evap system dodge has some of the worst I'seen . it doesnt take much for a small leak to register. good luck
SOURCE: 01 dodge ram 3.9 moter check engine light
Did you clear the code after replacing the gas cap and cracked hose?
You can do this with an OBD-II scanner from Walmart which costs under $100, or have the auto parts store do it that you bought your parts from if they are willing.
There will likely be no noticeable symptoms other than the Malfunction Indicator Lamp (MIL). This is because the EVAP system is a closed system and only controls fuel tank
vapors, not engine management.
Causes
Usually this P0456 code is caused by an incorrect or faulty gas cap. Filling the fuel tank with the engine running could conceivable cause this code as well or if the cap wasn't properly tightened. Any of the following could also be the cause:
First, using a scan tool activate the vent solenoid, sealing the system. Then monitor the fuel tank pressure (FTP) sensor. If the system is sealing properly, the number will stay consistent. If is isn't, the pressure sensor will show that as well. If the system slowly leaks, use a smoke machine and watch for smoke exiting the system at any EVAP component. Any where there is smoke exiting the system, that is the faulty component. Do not pressurize the EVAP system with air pressure. Doing so can damage the purge and vent solenoids in the system.
Info found at: http://www.obd-codes.com/p0456
Maybe try cleaning, tightening, or replacing the gas cap first?
P0456 Article by Dale Toalston ASE Certified Technician
Evaporative Emissions System - Small leak detected
The Powertrain Control Module (PCM) at different times performs various tests on the EVAP system. OBD II Enhanced EVAP systems are in place to keep fuel tank vapors from venting into the atmosphere, and instead purges them into the engine to be burned. Regular pressure tests are conducted by the PCM to monitor the sealed system for leaks. The PCM monitors the EVAP system pressure by watching the fuel tank pressure (FTP) sensor. When the sensor indicates a small leak in the EVAP system, this code is set.
Potential Symptoms:
There will likely be no noticeable symptoms other than the Malfunction Indicator Lamp (MIL). This is because the EVAP system is a closed system and only controls fuel tank vapors, not engine management.
Causes:
Usually this P0456 code is caused by an incorrect or faulty gas cap. Filling the fuel tank with the engine running could conceivable cause this code as well or if the cap wasn't properly tightened. Any of the following could also be the cause: - A small leak in any of the EVAP hoses or fuel tank hoses - A small leak in the purge valve or vent valve - The EVAP Canister may be leaking Possible Solutions:
First, using a scan tool activate the vent solenoid, sealing the system. Then monitor the fuel tank pressure (FTP) sensor. If the system is sealing properly, the number will stay consistent. If is isn't, the pressure sensor will show that as well. If the system slowly leaks, use a smoke machine and watch for smoke exiting the system at any EVAP component. Any where there is smoke exiting the system, that is the faulty component. Do not pressurize the EVAP system with air pressure. Doing so can damage the purge and vent solenoids in the system.
with the engine running could conceivable cause this code as well or if the cap wasn't properly tightened. Any of the following could also be the cause: tank hoses
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