P0456 (permanent) - Evaporative Emission System Leak Detected (very small leak)

[Bee8point5]

My B8 just threw a P0456 along with a 02616 - Unlocking fuel tank cap. Assumption is COVID related lock downs caused my car to sit...a lot...and thus not be pressed in and out as often...since I simply have been re fueling at one quarter the usual frequency. This lack of action caused the small solenid to corrod and thus alert the computer as to the fuel door/cap not being "fully" closed shut and thus that a "small" gas leak is perceived [inferred]. Is replacing just the actuator assembly the correct DIY here?

This is the failing part, correct?

https://germanparts.ca/parts/b0402-8...door-actuator/

[Smac770]

02616 / 02615 - fuel filler door lock solenoid problems, replace the solenoid. Common issue with the early actuators; you posted the corrective part

But that'll have nothing to do with the EVAP system analysis. For the EVAP small leak DTC, you'll have to do the normal troubleshooting process. It may or may not be the gas cap.

[Bee8point5]

I see....I didn't think it was a mutually exclusive relationship. I suppose one aspect of this DIY is noting whether the EVAP small leak "disappears" following an actuator assembly replacement.

Would that be a good way of looking at it?

[Smac770]

You have a DTC for the actuator, you could replace it or ignore it. I had that DTC for a few years before the actuator pissed me off enough to replace it.

But that actuator will have nothing to do with the EVAP DTC. If you want to replace the actuator and see, go for it. You're still fixing something, so nothing lost.

Does the EVAP code come back if you clear it? It could be you simply didn't get a good gas cap seal one time; what's the fault frequency for that DTC? Just 1?

[Bee8point5]

So like can I ask what the official due diligence process is for assessing the P0456. Because a fuel flap actuator isn't really a hard fix. The more technical stuff I wouldn't even know how to analyze.

[Bee8point5]

Update: cleared MILs with Carista. See how many days before it re surfaces?

[Smac770]

That's above my experience level to deliver an EVAP small leak diagnostic class.
I imagine it commonly comes down to the gas cap or the N80 purge valve.

For our engines, we have:

P0442 Evaporative Emission System Leak Detected (small leak)
Time for pressure drop < 1.55 - 1.75 Sec.

P0455 Evaporative Emission System Leak Detected (gross leak/no flow)
Time for pressure drop < 0.95 Sec.

P0456 Evaporative Emission System Leak Detected (very small leak)
Time for pressure drop < 4.5 - 6.0 Sec.

The EVAP system is covered in the Fuel Supply System repair manual.

I imagine there's a test you can manually initiate through VCDS, but I have no idea what/where it is, presumably under output tests. So if I wanted to guess if it was at the N80, I'd disconnect the N80 and plug that line which goes to the N80 then run the test. See if it now says no leak.

It's not a DTC I've had to personally resolve, so just speculation on how I'd approach it if it came up. If you do try to use a smoke test, make sure it's a low pressure smoke delivery, not more than 1 or 2 psi, or you're going to end up with a P0455. :-)