Ok, I was driving home yesterday after a 4 hour trip and boom check light comes on. Took it to autozone and they told me could be the gas cap small vacuum leak. Now I know it could be minor and i usually don't care about things so minor but the B5 s4 is a weird car so this is gonna sound dumb but can this in anyway be connected to turbo boost leak as im still on my stock turbos and there is 144k miles on my car. Please help.

 

P0442 is an EVAP leak; from your emissions control. Check your spider hose in the back of the intake manifold for any cracks (its a common occurrence for this engine)

 

yeah i think if your spider hose was leaking youd get a P0171 and P0174 for running lean... motts right.. its an EVAP leak... probably bad gas cap or your re-fueled with your car running..

 

Thanks guys, I think it is the gas cap because the last person to fill it was my girlfriend before we left for the long drive so im thinking she did not tighten it. I had it reset and have been driving it for about a day and a half and the light didn't pop on yet. Thanks bigern for the codes the spider hoses would set off because thats the only other thing i thought could of been leaking but the only codes that came on were p0442 so thats good.