[Doug D]

P0456 - Evaporative Emissions System - Small leak detected

 

[nrgbaldwin]

Thanks Doug!! So I am guessing that this means that I have a cracked hose or loose fitting somewhere. Maybe this explains why I have been getting all those 'gascap' warnings. Anyone have any idea as to where this could possibly be?? I haven't a clue as to where to look first.

Nance

 

[Doug D]

Since it's a "small leak" have you tried replacing the gas cap? If it's not the gas cap, you might want to have a dealer perform a "smoke test" which allow the leak to be found easier.

 

[ImperialCrown]

There should be a vacuum hose routing label under the hood. It could be any of the fuel vapor carrying hoses to or from the charcoal canister/fuel tank/purge solenoid valve, It could be the components themselves, but that is rare. The rubber hose can dry rot and crack at the ends where they push onto fittings.
The gas cap may have a pin hole also. A breach-to-air of .020" opening can set this code. It can be very hard to see, but a good visual inspection may find it and is a good place to start.

 

[scarlott]

no codes on mine at present but do have the gascap light on replaced gascap now can someone tell me how to reset the light ? Thanks

 

[ImperialCrown]

If the gascap was the evaporative leak problem, the light should go out within 2 or 3 OBD II evaporative leak monitor 'good trips'. I don't think that you can force the light off without a scan tool.


OBD II Drive Cycle An OBD II Drive Cycle is an extended set of driving procedures that takes into consideration the various types of driving conditions encountered in real life. These conditions may include starting the vehicle when it is cold, driving the vehicle at a steady speed: (cruising), accelerating, etc. An OBD II Drive Cycle begins when the ignition key is turned 'On': (when cold) and ends when the vehicle has been driven in such a way as to have all the Enabling Criteria met for all its applicable Monitors. Only those trips that provide the Enabling Criteria for all Monitors applicable to the vehicle to run and complete their individual diagnostic tests qualify as an OBD II Drive Cycle. OBD II Drive Cycle requirements vary from one model of vehicle to another. Vehicle manufacturers set these procedures. Consult your vehicle's service manual for OBD II Drive Cycle procedures. Do not confuse a 'Trip' Drive Cycle with an OBD II Drive Cycle. A 'Trip' Drive Cycle provides the 'Enabling Criteria' for one specific Monitor to run and complete its diagnostic testing. An OBD II Drive Cycle must meet the 'Enabling Criteria' for all Monitors on a particular vehicle to run and complete their diagnostic testing.

 

[scarlott]

Thanks Imperial Crown Had made some short (5 mile or so ) trips and was still on have a pretty good scan toll but no codes showing at this point did have the small leak code show and cleared since then put new gascap but no new codes guess its just wait and see.

 

[vipergg]

Same issue on a 2007 sxt , looked at the gas cap , looks ok . Looked at the hoses going into the cannister under the car those look ok and in pretty good condition with no visible cracks. May just try a new cap even though the current one looks ok and still clicks when turned. Otherwise into the dealer it goes.

 

[mgbmike]

I went through this a couple of weeks ago. I showed a P0442 code. Swapped out the gas cap with a new one, erased the code with my scanner, but the code came back.
After having the van smoke tested it turned out to be a crack in the the fuel filler pipe.

 

[ImperialCrown]

The gascap needs to be airtight. You shouldn't be able to blow through it at all from the filler tube side. A small leak = .020" pinhole.
The NVLD switch is another fairly common failure.
The smoke test is the best diagnosis for an evaporative leak when a visual inspection reveals nothing.