Intermitten P0446 Code

[tejawxyz]

The first time it came on, my gas cap was bent, so it wont fit properly. I bought a new one and it fixed the CEL. A couple of months since, its been coming on and going off. Is this the charcoal canister fault code? If so, what is supposed to be done?

Thanks

[fun2drive]

From the search section:
If you search p0446 this is the 2nd post you will see besides yours, hopefully it will help.
http://forums.bimmerforums.com/forum...ighlight=p0446

P0446 Evaporative Emission Control System Vent Control Circuit Malfunction
Purge Flow Sensor Circuit Range/Performance
Charcoal Canister aka Carbon Collector Canister / Evaporator Valve
DIY :
1. Remove your spare tire.
2. You will now see an oval shaped black plastic covering with a threaded rod coming out of the middle.
3. Remove the nut and washer.
4. On the right hand side of the oval plastic piece you will see a flat covering that is molded to the oval piece. There is a plastic nut holding the end of this down. Remove that nut.
5. Pull the plastic piece straight up and out.
6. You will now see the charcoal canister with 3 lines going into it from the right hand side of the car (passenger side).
7. The two thinner lines (same size) have metal hose clamps on them.
8. They are snug, but with a screwdriver (flat) you can gently work the hoses off without removing the clamps.
9. Next, remove the thicker hose. (it just pulls off, wiggling side to side helps)
10. During the hose removal you may want to have a friend hold up the canister. It is not secured to the car and can slide up the threaded rod.
11. Once your lines are off, remove the canister by lifting straight up.
12. Installation is opposite of removal.
NOTE: There may be gas vapor in these lines when disconnected!
THUS: Turn off all your stereo equipment if you have any in your trunk...and for god sakes man don't smoke!
Lastly, you will not clear your Check Engine light right away. It will take a day or so of starts for the system to recognize the problem has been resolved.

[AgentHubcap]

Is there a way to test the charcoal canister? I've asked before but never really gotten an answer.

The reason why I ask is that code could be a few other things. There is an expansion tank in the fender, and a number of hoses that are related. Without being able to test the individual components you'll have to replace things and hope it fixes it. That tends to get expnesive

[Tongboy]

you can test the charcoal canister itself by applying 12v across the two wires and listening for it to kick over - it's pretty noisy when you've removed all the insulation.

testing the other pieces in the evap system are a bit more complicated - the purge valve is straight forward but the evap pressure sensor takes some tools.

[e36323is]

Hi,
I know its been awhile since this was posted, but I was wondering if replacing just the shut off valve would do the trick? I looked online, and a new canister is about $350, while shut off valve is just $70.

Hope someone has an answer and thanks in advance!

[berny2435]

bumping this cuz I had the same issue with intermittent P0446

I've found that my P0446 code went away after I took the Charcoal Canister Valve out, cleaned it, lubbed the stopper with dielectric grease, flipped and greased the 2 outer O-rings as well. Stuck it back in and no code for two weeks. I also played with the fuel tank breather valve wire connections but I don't think that had anything to do with it.

So clean and lube #2 here http://www.realoem.com/bmw/showparts...02&hg=16&fg=10

Play with and check the cleanliness of the connections on Fuel tank Breather valve #1 shown here http://www.realoem.com/bmw/showparts...72&hg=13&fg=15

[Nline6]

I am still having issues with this same fault code. I have replaced the fuel cap and the Valve, and still get the code thrown every few days. It does clear itself, only to come back in a day or so.

[berny2435]

I am still having issues with this same fault code. I have replaced the fuel cap and the Valve, and still get the code thrown every few days. It does clear itself, only to come back in a day or so.

Which Valve?
do what I did in the post before yours and report back. Easy to do. The hardest thing is lifting the damn spare out.. .
I continue to have no code. I believe it was purely the valve on the Charcoal Canister that was giving me fits.

Nice M3/4/5 BTW!

[Butters Stoch]

I has a spare charcoal canister kicking around.

[Mfonk]

I have been having the same issue. New gas cap, charcoal valve, replaced lines, cleaned one-way valve and replaced purge valve and cel light comes on every few days only to clear itself after 3 cycles. Any ideas?

[berny2435]

Mine still comes on. Most of the time when it comes on, it's shortly after I have filled completely up with gas.

[Mfonk]

Read this in another post. Worth a try I guess.

"P0446 - shut off valve stuck closed or sensor bad or wires or purge

but another fixes I found was this ...

I fought with this same problem for over a year and just got it resolved this past weekend. First, the EVAP shutoff valve is located in the trunk under the spare tire and the round plastic cover - it is fitted into the side of the activated charcoal canister. The valve is around $100 new from the dealer. However DO NOT BOTHER REPLACING IT - IT WILL NOT SOLVE YOUR PROBLEM.

The problem is with the DME. The CE light gets set because the DME thinks the fuel tank pressure is too low - has a vacume - (the opposit of the "leak" code you get when you leave your gas cap off). I changed the fuel tank pressure sensor, the EVAP shutoff valve and the purge valve and this still did not help.

Ok, drumroll please... The fix is a DME reprograming. The dealer told me on Sat. that a service bullitin came out on this telling the BMW service folks that the DME was too sensitive to this low pressure situation, and that the DME "patch" would resolve it. They reprogrammed the DME on Sat. and NO CHECK ENGINE LIGHT for the first time in a year! Charged me one hour labor to fix - $95. Take the car to the dealer and tell them to look up the service bulletin and save yourself a ton of money and aggravation. Make sure they look the bulletin up and fix it, not just reset the CE."

[joenationwide]

Read this in another post. Worth a try I guess.

"P0446 - shut off valve stuck closed or sensor bad or wires or purge

but another fixes I found was this ...

I fought with this same problem for over a year and just got it resolved this past weekend. First, the EVAP shutoff valve is located in the trunk under the spare tire and the round plastic cover - it is fitted into the side of the activated charcoal canister. The valve is around $100 new from the dealer. However DO NOT BOTHER REPLACING IT - IT WILL NOT SOLVE YOUR PROBLEM.

The problem is with the DME. The CE light gets set because the DME thinks the fuel tank pressure is too low - has a vacume - (the opposit of the "leak" code you get when you leave your gas cap off). I changed the fuel tank pressure sensor, the EVAP shutoff valve and the purge valve and this still did not help.

Ok, drumroll please... The fix is a DME reprograming. The dealer told me on Sat. that a service bullitin came out on this telling the BMW service folks that the DME was too sensitive to this low pressure situation, and that the DME "patch" would resolve it. They reprogrammed the DME on Sat. and NO CHECK ENGINE LIGHT for the first time in a year! Charged me one hour labor to fix - $95. Take the car to the dealer and tell them to look up the service bulletin and save yourself a ton of money and aggravation. Make sure they look the bulletin up and fix it, not just reset the CE."

I think this is my problem, because I've already checked the shut off valve, purge valve, and all the lines.
Do you know the number of the service bulletin?

[berny2435]

I wonder if their fix woukd get rid of my Dinan tune?

[joenationwide]

I think this is my problem, because I've already checked the shut off valve, purge valve, and all the lines.
Do you know the number of the service bulletin?

I think I found it. TSB 122099

http://www.bimmerforums.com/forum/sh...vice-Bulletins

[shogun]

more info https://www.bimmerforums.com/forum/s...picking-up-car

Just for reference here the TSB S52 ENGINE PRODUCRD 2/98-9/98
TSB 122099 Bulletin Date: 19990801 Category: 116200 ELECTRICAL SYSTEM: IGNITION : MODULE
Summary: SUBJECT ON SHUT-OFF VALVE FAULT CODE SET IN ENGINE CONTROL MODULE (ECM/DME) ON MODEL WITH S52 ENGINE PRODUCRD 2/98-9/98. *MJS
-----------------
This might help anyone that has had the intermittent CEL and has pulled the OBD-II code P0446 - Evap valve stuck closed SHUT-OFF VALVE FAULT CODE SET IN ECM/DME
MODEL AFFECTED: S52 engine
FAULT: The check engine light is on and the fault code: FC 253-shut-off valve, activated charcoal filter jammed shut is set in the ECM/DME.
CAUSE: Tank pressure sensor voltage threshold inside the DME program is to high.
SOLUTION: Check overall operation of the system, if no faults are found then the DME needs reprogramming.