So I've been chasing this annoying code for way too long: P0442 - Porsche Fault Code 97 - Tank Vent System (Minor Leak). I have already replaced the gas cap, purge valve near the TB as well as another valve that sits right at the gas tank fill neck. The code seems to show up whenever it wants. I've gone for weeks not seeing anything and also had it come on every other day. Car runs perfectly fine but I want to get this fixed and it seems like the next logical step is to smoke test the EVAP system. My question is: what is the preferred entry point for the smoke test? I've hooked up my smoke machine before to the TB when testing some of the vacuum system but was curious if there was a different procedure for the EVAP. Appreciate any insights on this!

 

I normally go through the test port if it exists on the car.
The 996 doesn't have one though, I unhook the purge valve near the TB and go through it.
But I recommend not using an air compressor to do the smoke test for EVAP systems.
It's not recommended to push smoke using oxygen into the fuel tank, especially if the fuel level is low.
I know lots of people do it without any issues, but it's not considered safe, and I won't do it.
I have a bottle of nitrogen that I use just for EVAP testing.

 

Thanks - I was thinking of going through the purge valve as well as that leads directly to the EVAP system and should be more effective, I think.

I will not be using an air compressor to move the smoke into the engine so safe there but appreciate the warning! I actually have a home made smoke machine that uses a small bike pump to move the smoke so very minimal amount of pressure will be used. Will give this a try soon and hope to find the culprit!

 

Is your replacement cap a Porsche cap? A few months ago I got distracted while fueling and drove off without the cap (tether broke). I bought a Stant #826 the next day which fit perfectly even making a hiss when removing. I still kept getting the code every ~100mi or so. I was going to replace the purge valve but figured since it wasn't a problem before let's try easiest/cheapest first so I ordered a Porsche cap (with tether). A few k miles now and no codes since. As with many other parts our cars even like genuine Porsche gas caps.

 

Yes, using a genuine Porsche gas cap. I think the price delta was like $3 between that and other options so just got the real deal. It was the fist thing I replaced but no dice.

 

Screen shot for future reference! Thanks Tex. I haven’t been gutsy enough to smoke the EVAP system yet.