Hissing from fuel filler cap

[BigJC]

My car has recently taken to hissing from the plastic fuel filler cap. Will this cause any problems?

 

[AndyMac]

Yes, it's most likely a duff recirculation/solenoid valve:
http://www.audi-sport.net/vb/showthread.php?t=21830&highlight=hissing

 

[BigJC]

Cheers, it'll be off to the stealers on Monday then!