[carringb]

Is there a check valve in the Webasto line? The fuel tank is under vaccine while driving. If it doesn’t pull vacuum it throws an evap code.

 

[carringb]

There’s no check valve just a fuel filter. And I haven’t fired the heater up yet so it hasn’t pulled fuel through the lines yet. Could that cause the code as well?

Yeah, if you haven't pulled fuel into the Webasto pump, then it's probably not creating a seal yet.