mr.horsepower

Hi,

I have a sporadic fault code on my 997 GT3 that say P0456 Tank system micro leak (exceeds limit value).
Anyone heard of that before?

Check engine light comes on, but the car is acting normal. I've changed the fuel filler cap.

I also note that when I'm filling gasoline, I hear a whistling noise from the ventilation. Like it's not flowing enough air.
I have to hold back on the pistol and it takes like 10min to fill the tank (90L.)

noro

I had that pop up once, reset it, refueled and never come back. Your might be real, are you getting them over and over after resets?

mr.horsepower

Some times it can go longer time, and some times shorter.
It have also gone after a refuel without resetting.

Now the last time it have been gone for over a week and some driveouts.
I have a feeling that rain can trigger it. But I try to avoid driving in the rain.

noro

You can always get one of those smoke test machines and use to determine a leak.... setup is a slight pain but makes it a snap finding leaks.