rysagreg

Hi All –
My engine light is on and the code that appears is P0442 (Fuel Tank Ventilation System (Micro-leak) - Below Lower Limit). I replaced the gas cap last week from Pelican and then cleared the code. Within 100 miles (day or two of driving), the light came back on. Last evening I removed the front passenger tire and wheel well cover and looked around the canister, fuel valve and all the hoses and connections. Everything looked good, tight, no signs of cracks or wear and remarkably clean under there. Is there anything else I should look at? Perhaps in or around the engine area? The car runs great, no problems at all, except the engine light comes on. It is a 2002 996, Cab, Tip, 62k miles, daily driver. Any help would be appreciated……Thanks, Greg

fpb111

check the hoses and around this part, and the valve itself.
http://forums.pelicanparts.com/porsc...gravation.html

also read through this thread:
https://rennlist.com/forums/996-foru...r-gas-cap.html

PelicanParts.com

May be worth another look/inspection of the fuel filler vent valve area. Read further details here, 996 fuel filler vent (bleeder) valve

Or take a minute to view this video from another perspective here:

Hope that helps! Keep us posted as you trouble-shoot.

Mark/Pelican Parts

rysagreg

Thanks Mark....I did see this video this morning after Frank (Fpb111) responded with a link. The valve and hoses cosmetically looked good and it was very clean up in that area when I looked last night. However, if the valve isn't closing/opening, I would not see that since it's internal. I'm leaning on just purchasing the vent filler valve part from you guy's (Pelican) and keeping my fingers crossed that it does the trick. I'll probably wait a few more days and see if anyone has any other ideas or experienced something similiar. The second best thing from owning a Porsche is this site! So much great information on here especially for people who like to do it yourself stuff. Thanks again Mark.

fpb111

Could also be the valve at the other end by the throttle body. Check post #82 on. Especially #103
https://rennlist.com/forums/996-foru...em-pics-7.html

this part
http://www.pelicanparts.com/cgi-bin/...1999-05)%20%20

fpb111

If the one by the fuel filler fails completely you wil probably get a P0455 Large air leak.

see this info about evap purge systems
http://www.obd-codes.com/p0442

rysagreg

Frank - Very cool and thank you for taking the time to research this, especially so detailed on the posting numbers. I did look at both and loved it. I am definitely going to look at this tomorrow afternoon. That would be great if that is the problem.....easy fix and probably cheaper to replace than the fuel filler valve. Good timing too, I was planning on removing the large air intake piece of plastic or shroud and take a peek at the water pump area. I saw a post today regarding water pump issues over 60k miles and I thought it would be good at least take a peek and inspect since I am north 60k miles (preventative maintenance). I'll send a separate post out tomorrow to get opinions and make sure I'm not worrying to much! Thanks again Frank, I'll post results tomorrow. Enjoy your weekend.

rysagreg

Hi Frank -
I think you may have found my problem! The post you mentioned previous on post #103 shows a picture of the "Regeneration Valve - 996 110 129 52 M100". I'm attaching a picture of mine. If you look at the end of the orange pointer, hopefully you can see the kink in the line. Could this throw a minor leak error code P0442? At first, and after reading what the regeneration valve does, it appears to me that this may be the problem. If so, I greatly thank you !!!!!!!!!!

rysagreg

Oops! After I sent the last post I went and looked more closely and found out that the kinked tube is just covering wire. I assumed it was an air or vent tube. Just plastic wire covering is all that it is. Back to square one....probably my next step will replacing the fuel valve assembly. I'm in no rush, car runs great, just annoying engine light. Welcome any other posts or ideas....Greg

haimiko

I have the same exact problem. I tried replacing the gas cap and the bleeder valve per Pelican Parts video but after a few miles I got the error again. Any other suggestions

rysagreg

My light is still on. I have not had the time to take it to the dealership to see what they find. The car runs great, but the light is still bugging me. Hopefully someone on here can advise us both.....new gas cap and bleeder valve and the light still comes on.

haimiko

Yeh. Driving to Scottsdale is a hassle . There are a few other fuel valves I could try but they are too $$ for guessing. I'd like to know how to narrow it down without replacing the whole fuel system. I looked it up in "Bentley Publishing" 911 book and all they have is diagnostic voltages that are known to trigger the even but no info on troubleshooting.

fpb111

Change your purge valve except for lines it's the only "old" thing left on yours.

Most of the time it is one of the three, Gas cap, Vent valve, Purge valve that causes P0442-445 (Small – Large air leak) It could also be cracked vacuum lines, most often in the engine compartment caused by heat vibration etc…

What it really is telling you is that the Government suspects that you are polluting more than your fair share.
You aren’t leaking air but potentially allowing Fuel fumes into the atmosphere by having a compromised Evaporative Recovery System.

The system works something like this:
Car is fully warmed up. Fuel is between ¾ and ¼ full. Computer says parameters are right GO/DO Evap system check.

1. The vent valve closes

2. The purge valve opens to build vacuum in the system, charcoal can , hoses, etc.

3. The purge valves closes after a certain level of vacuum builds. If vacuum doesn’t build DANGER, Danger Will Rogers!! The computer throws a Large air leak Check Engine Light (CEL) p0455 is set

4. Purge valve closes when x inche of vacuum is reached. Then Vacuum is monitored for XX time.

5. If vacuum is stable, system normal is set. If not one of the Evap codes is set, P0442 small leak to … Drone Strike!

The gas cap is often the culprit because it lives the hardest life.

The vent valve is closest to the dirty atmosphere and is allowing that air into the tank to replace the fuel used, so that you don’t create an unwanted vacuum that would impede fuel flow. This often allows dirt to accumulate in the valve's seat causing leaks.

The purge valve is the busiest valve. This is a pintle valve, like a fuel injector. When everything is up and running correctly it is often clattering away like a crazed telegraph operator. This valve controls air or air/fuel mix purged (sucked) from the charcoal can back to the intake manifold. The amount of fuel vapor depends on how much fuel has made its way to the charcoal can.

With a small air leak the solenoid part of the valve is often working but the seat is worn/dirty and can’t hold a vacuum long enough to pass the test cycle.

Vent valve pic in post #3 above.

Purge valve in pic 3-4 post 103 here on page 7
https://rennlist.com/forums/996-foru...em-pics-7.html

5CHN3LL

Nominated for best metaphor of the month...

haimiko

Thanks fpb111. Are you referring to the EVAP canister purge valve or the operating purge valve?