I have a 2015 3.5L Ecoboost F150 and got a P0456 (Small Evap Leak) code two months ago. I cleaned the round capless filler flap and cleared the code but it came back. Then I replaced the purge control valve (BL3Z-9B325-C) on the top of the engine. Cleared the code and it went away for a few weeks but came back again. I've got to get the truck emissions tested by the end of November and need to get this figured out.

I was doing some more digging into the problem this morning and found a video that showed that there's actually two flaps on/in this capless filler neck, the outer round larger flap and then deeper inside a smaller inner flap. But the video didn't say what Ford vehicle it was or what year. Anyway, the smaller inner flap should only open if you insert the gas pump filler nozzle because it compresses two tabs that allows that inner flap to open. Supposedly it's a safety guard to stop people from stealing gas. Soooo I went outside to check mine and I am able to push open the inner flap but couldn't see any tabs. Admittedly it was dark out and I couldn't see well with my phone light.

On a 2015 F150, should you be able to push open that inner, smaller flap with just your finger? If not then that's probably what's causing my code.

Thanks!

 

Can't comment on the operation of the smaller flap but his is what the WSM says:

P0456 - Evaporative Emission System Leak Detected (Very Small Leak)

Description:
This DTC sets when a fuel vapor leak from an opening as small as 0.508 mm (0.020") is detected by the EVAP running loss monitor test.

Possible Causes:

• Very small holes or cuts in the fuel vapor hoses or tubes
• Loose fuel vapor hose or tube connections to the EVAP system components
• EVAP system component seals leaking

Diagnostic Aids:
Check for a missing fuel filler cap or the integrity of the cap (if equipped). Verify the capless fuel tank filler pipe is sealed correctly (if equipped). Install and remove the supplemental fueling adapter five times in the capless fuel tank filler pipe to clear debris on the seal. Refer to the Owner Literature for the location of the supplemental fueling adapter in the vehicle. Check for loose or damaged vapor hoses. Visually inspect the EVAP canister inlet port, EVAP canister vent valve filter, and EVAP canister vent hose assembly for contamination or debris.

 

Thanks 52merc. Much appreciated

I've been through this truck head almost top to bottom over the years and don't recall ever finding the supplemental fueling adapter (fuel funnel). My kid has a 2016 2.7L F150 and I'm going to have him check that inner flap when he gets home from work. In the mean time I think I'll spay some WD40 on it to see if maybe it's just gunked up and sticking.

 

There's another valve by the gas tank, and it could be the charcoal cannister as well.

 

Just a comment.
A very small leak will not return a code very quickly after you do a clear, hence the delay in getting a code.
Using a hand Vacuum pump to test sections of the system and valves for leak-down, may be needed.
Get a photo blow-up of the system to see what and where the parts are.
Good luck.

 

Thanks everyone.

Anyone know if the emissions testing place will ding me on a pending code? I haven't needed an emissions test in almost 20 years.

I do have a hand vac so I'll look for a diagram of the emissions system and start testing. And there's been a few times in the past where a smoke machine would
have been nice on a few of my previous vehicles. I guess it's time to finally purchase one.

 

P0456 I think is specific to an engine off fuel vapor pressure leak test. The PCM undergoes a 45 minute test while the engine is off by closing the vent solenoid sealing off the system. If pressure doesn't reach .7 in of H2O, the positive pass threshold, the PCM will open, deinergize, the vent solenoid, release the pressure and set the code P0456.

 

Yes, in my experience codes can not be 'pending'. They need to set which will either mark them ready or flag a CEL. You can check the monitor status with most OBD scanners, Forscan, etc.

This is to prevent someone from clearing CELs for a P0420 cat issue / etc and then immediately going in for an emissions test before the ECU has finished evaluating whether the issue persists.

There are some fine details like in CA, depending on year, a certain number of items can be not ready (such as 1-2, but not all).

 

Check out http://WWW.motor.COM/magazine-summar...ation-testing/
Always a source of accurate info on many systems, not found elsewhere.

If the link does not get you there, try a regular search that worked for me.
Good luck.

 

Your link gives me a 404 error. Could you check it again?