During a recent scan I got the following fault code:
"Address 01: Engine Labels: 4D0-907-560-BGH.lbl
Part No SW: 4D0 907 560 DD HW:
Component: 4.2L V8/5V G 0030
Revision: 00000000 Serial number: VWZ3Z0E7300196
Shop #: WSC 01065 000 00000
1 Fault Found:
16840 - EVAP System
P0456 - 002 - Very Small Leak Detected - Intermittent
Readiness: 0000 0000"
After reset the code has not come back, and there are no other symptoms at the moment. The only abnormality I can recall is that back in February upon leaving the underground garage to og home after a full day's work, I got the "check your fuel cap" message and icon in the instrument panel. In both cases it happened at exactly the same point in my route home, approx. 5 minutes after leaving the garage, which is at a pretty constant 78 F, into outside temperature in the lower thirties. In both cases, the message and icon disappeared after rebooting (i.e. turning off engine, pulling key out of ignition, then turning on again).
My guess is that the EVAP fault code is somehow related, and may be triggered by a sharp change in the fuel tank's internal pressure due to the sudden significant change in outside temperature. Still, I wodner why it has never happened before in almost seven years of ownership, and only started this past winter, which was quite mild by local standards. Thoughts?