Fault code P 0446

[greenrob]

Morning all, Just found engine fault code P0446 on my 1998 986 with tip. Description reads Evap canister shutoff value below lower limits. I would welcome any ideas on a solution.

Thanks in advance!

Robert

[JFP in PA]

Quick question: Did this code trip just after filling the tank? Reason I ask is that the early cars seem more prone to throw this code after a fill up, and when that happens the code is usually a “ghost” code caused by a momentary purge line blockage during the filling process. If it was, clear the code and it most likely will not come back, at least until your next fill up. If the code comes back, see below.

Normally, if the P0446 code is thrown, it is caused by a blockage if the air purge line in the EVAP system. This code can often be corrected by simply blowing air through the purge line, which is in the engine bay, under the intake manifold. A bit of a pain in the butt to get at, but a quick “pffft” of compressed air will take care of the issue.

[greenrob]

Quick question: Did this code trip just after filling the tank? Reason I ask is that the early cars seem more prone to throw this code after a fill up, and when that happens the code is usually a "ghost" code caused by a momentary purge line blockage during the filling process. If it was, clear the code and it most likely will not come back, at least until your next fill up. If the code comes back, see below.

Normally, if the P0446 code is thrown, it is caused by a blockage if the air purge line in the EVAP system. This code can often be corrected by simply blowing air through the purge line, which is in the engine bay, under the intake manifold. A bit of a pain in the butt to get at, but a quick "pffft" of compressed air will take care of the issue.

[greenrob]

Yes thats when it the code popped. I reset the code and after a short 10 min drive it has not returned. I hope thats all it was and thank you for you reply.

:thankyou:

[JFP in PA]

You will probably be fine; as I mentioned, this is a common issue.

[mcmike27]

Our 98 986 just did the EXACT same thing.....I was not paying attention during a fill up and the shut off didnt work quite right and I had a very slight overfill. I drove home from the gas station and all was fine until the next morning and there is was CEL light and the P0446 code. I did as Jeff and you did...reset and it hasnt happened again.

This was the second time it has occurred both after slightly overfilling the tank.

Glad your was as easily fixed as mine.

:)

Edited August 1, 2011 by mcmike27

[adonkin]

:help: I'm another one cursed by the glowing CEL beast with a P0446 code, this one accompanied by P1128 and P1130. I've read all the posts in the various threads on a P0446 search and now my 2000 986

base is also stalling and hard starting. The current symptoms were proceeded by some unusual behavior that's grown worse over the last 6 months.

History: It started with an annoying whistle (like blowing across the top of a bottle) coming from the EVAP vent under the gas filler door. It was suggested that I stuff a small piece of open-cell foam into the opening to damp the resonance and that worked like a charm for the last couple of years with No CELs. Thanks to the board! :notworthy: But all changed one day after restarting the car after a trip through a high blast "touchless" car wash. But I've done this many times before. This one threw the CEL but the car was still running fine. That is till the first gas fill-up! I never top and always pump my own but after my standard fill of Sunoco Ultra my box won't start for the first time in the 4 years that I've owned her. :huh: Eventually, in a panic, I held the gas peddle to the floor (like in the older flooded carb days) and cranked and cranked and cranked till it finally caught with much jazzing the throttle to keep it alive for a minute or two. Then absolutely no more issues with starting or driving till the next fill-up and there I have to go through the floor it and crank routine. We read and interpreted the codes (above), then read through all the related posts and narrowed the fault to maybe a vacuum leak (full disclosure: I did change out the coolant recovery tank a few hundred miles ago) or one of the three solenoid controlled valves in the EVAP system. After scouring the lines for leaks, finding none, a call to Sunset (a board sponsor) confirmed my suspicion that the culprit was most likely the purge control valve located under the left intake manifold. They mentioned they were selling many of these compared to the other two (under the right front inner wheel well). The responses from the much appreciated, experienced, and learned folk on this board have found this valve to a common failure point evidenced by these symptoms and codes.

Sunset sent me a replacement (996 110 129 06) and I set about to swapping this out. Now here's my current dilemma. The attached pipe to this valve is pinned to the underside of the intake manifold with a metal strap/rubber bushing combo with a screw or bolt which appears to be unremovable without removing the intake manifold! Boy did this job balloon by several orders of magnitude. That job isn't even covered in Bentley's. Am I wrong about this? I could just cut the pipe and see if I can route the new one around this clamp. But I also read JFP in PA's response which suggested just a "pffft" of compressed air through the line should take care of things. Really? I assumed the air blast should come from the manifold end (reverse the normal flow direction) but with the under-car end open or closed? I don't want to pull that intake if I don't have to and any help will certainly be appreciated.

Alan

[JFP in PA]

It really doesn't seem to make a lot of difference which end you put the air in as long as the line is clear..............

Getting at the line and purge air valve under the manifold is not fun, as you have discovered. I have not seen it written up anywhere other than the OEM service manual set.

Edited April 5, 2012 by JFP in PA

[adonkin]

Thanks for hanging on to this thread, JFP. I plan to break the connection under the car and blow back towards the intake above the manifold split. But replacing this baby looks like a PITA. Have you done the R&R?

[JFP in PA]

No, I have never had to change out the valve, but I have blown a few out over the years.

[adonkin]

I'll give the air blast a try this weekend and get back with the results. Is it really a no-no to reset the fault codes with a 30 second battery disconnect (still preserving the radio code)? Thanks for the help!

[logray]

If you know the fault codes and have read them out then no generally speaking clearing the cel with the battery is OK.

But if you are blindly clearing the CEL to solve a problem without first reading the codes, you might erase valuable codes that could have helped you solve the problem. By clearing them, they are gone and you would have to wait for them to reoccur again.

There are some "cheap readers" out there that don't clear, only read... so in those cases unplugging the battery is the way to go.

You won't preserve the radio code when you unplug the battery, but thats farily easily solvable usually if you post your radio info in the radio fAQ here.

[adonkin]

Thanks logray. I've got the codes (posted in my first reply) and read (from Wayne Dempsey's 101 Boxster Projects - I think) that if you disconnect the battery for >20 secs. but less than 50 secs., you'll erase the CEL codes and preserve the radio code.

Either way, if I loose it, I have the proper radio code somewhere in my docs. or dig into the radio FAQs you mentioned if I can't find that.