Persistent P0447, even after CEL reset - Subaru WRX Forum
 
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post #1 of 8 Old 10-23-2006, 09:12 PM Thread Starter
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Persistent P0447, even after CEL reset

WRXTuners n00b here. Gotten great info so far lurking and reading.

I searched for this code in the forums, but didn't find anything.

Been having a persistent P0447 code (pulled with friend's OBD reader) since the temps have gone down in the 40s here in WV.

I see from the OBD Guide that it's "Evaporative emission control system vent control low input"

I seem to recall reading that this could be a loose gas cap. I tried to really put the cap in tight, reset the CEL, but it pops right back up.

It's not affecting performance that I can tell, but the CEL is annoying.

No real mods to speak of that I would think set this off. Is it just the temps and a leaky gas cap maybe? Loose hose in the fuel system vent? Time for a visit to the dealer?

Any ideas?

TIA,

-Karl
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post #2 of 8 Old 10-24-2006, 12:29 PM
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Go buy another gas cap and see if it goes away. Its like 10 bucks at autozone or something. If that still does clear the code then go to the dealer if you still have warranty. Or just go the dealer because you have warranty anyway, but you might have to pay for inspection 100 bucks.
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post #3 of 8 Old 10-24-2006, 05:01 PM
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Quote:
Originally Posted by WVWRX
WRXTuners n00b here. Gotten great info so far lurking and reading.

I searched for this code in the forums, but didn't find anything.

Been having a persistent P0447 code (pulled with friend's OBD reader) since the temps have gone down in the 40s here in WV.

I see from the OBD Guide that it's "Evaporative emission control system vent control low input"

I seem to recall reading that this could be a loose gas cap. I tried to really put the cap in tight, reset the CEL, but it pops right back up.

It's not affecting performance that I can tell, but the CEL is annoying.

No real mods to speak of that I would think set this off. Is it just the temps and a leaky gas cap maybe? Loose hose in the fuel system vent? Time for a visit to the dealer?

Any ideas?

TIA,

-Karl
This might help. http://forums.nasioc.com/forums/show...ighlight=P0447

Homebrewed tuned with Opensource!
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post #4 of 8 Old 10-24-2006, 10:13 PM Thread Starter
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Thanks!

Thanks for the replies. I'll try the gas cap first. I checked the passenger side wheel well and it's pretty cruddy under there. I'll have to dig around see if there are loose connections.

-Karl
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post #5 of 8 Old 10-26-2006, 08:31 PM Thread Starter
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Update - new gas cap, no joy

Just a quick update...picked up a new gas cap, popped it on, cleared CEL with OBD tool...

Pops right back on.... P0447 again.

I'll have to dig a little more how this whole evaporative emission system works. I'll report back what I find.

As soon as I get done playing with my new UTEC, that is.

-Karl
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post #6 of 8 Old 05-05-2010, 12:56 PM
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P0447 Fix

So I too got the mysterious P0447 cel. Doing some reading I narrowed down the real problem and this is what I came up with. I have a 2002 WRX with 105k miles.

Background:
First off while there probably are some gas cap issues or leaking gas lines I believe that the majority of these faults are caused by bad wiring. This cel refers to a solenoid valve to check the fuel lines for leaks. I have read that it is only used when the car is first started up. From what I can gather it closes the valve checks a pressure sensor and then can determine if there are any leaks in the fuel / fuel return lines. If anyone wants to correct /clarify my understanding...please enlighten me.

Location:
The location of the valve is in the rear passenger side of the vehicle. There is no need to jack up the car or remove the wheel. Just get out some trusty card board and slide you head under the rear bumper. First you'll notice a black plastic box, slightly smaller than a shoe box. it will have a few hoses connected to it. I believe this is the evap cannister. Next to this box is a wire harness with a connector that is connected to the solenoid valve in question.

Inspection:
First thing to try is remove the connector from the solenoid valve and clean out all the crud in there. With the connector disconnected start the car. The connector hangs down enough to access it with a volt meter. Set the meter to VDC and measure the two pins in the connector. If everything is ok you should read 12v. I measured 0.47vdc when i checked. If you have 12v you most likely have a problem somewhere else and my advice won't help. How ever, if you read anthing other than 12v you have a problem.
TURN OFF THE CAR!!

Next slide back under the car with some liquid wrench and a 12mm socket with extension. Remember the black shoebox thing, there should be 3 12mm nuts holding it to the car. Two in the back and one in the front. Be careful when removing them because they are mounted to soft rubber/plastic dampening thingies.

The black box will drop down out of the way. Be careful not to flex the hoses too much. With the cannister removed the rest of the solenoid valve harness is exposed. You'll probably notice rust/dirt/crud hidden behind the box. I beleive this is because this area is not shielded from the rear tire and all kinds of slop gets thrown in this area.

Follow the harness from the solenoid valve connector up untill you get to a "Y" in the harness. You'll need to remove all the electrical tape from the connector to the "Y". Under the tape I found some split wire loom. This can be removed. (mine was completely filled with moist dirt. When the split loom is remove a solder joint will be revealed. My solder joint had failed it had turned green an the wire had broken from the joint. I don't know what clown installed this but....WRONG! It seemed to me the splash from the tire had gotten up into the wire harness and rotted out the solderjoint/wire.

I cut back the rotted wire. Stripped and tined the ends and soldered the 3 wires back together. Temporarilly I have covered them in heat shrink and electrical tape. After I got the wires soldered back together I bolted the cannister back up into the car.

I cleared the cel (I have an accessport) and started the car. EUREKA! Problem solved. I don't know if this solder hack job was done at the factory or from the dealer during a service but this is a bad location to just solder and tape. Before the winter I will be going back under there with some new split loom and some RTV and some electrical tape and try to water proof the begeezee out of it.

I'm gonna try to attach a photo of my adventure. Hope this helps.
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post #7 of 8 Old 05-04-2011, 10:49 AM
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P0447

What I have done is I went and researched it then found this bit about the gas cap, so I tightened it down checked it. It was still a problem, then I went around the block to get some gas through it to the sensors. Then shut off the car, reset the code VIA OBD2, and now it is gone so before replacement parts, I would advise this to try at least its more cost effective. I have tuned my car for me installed all of the parts myself to include my lightbar and such. The only difference that I do know about between your cars and mine is mine is a, 2002 Legacy GT, that I have custumized myself. Due to being so tall, I fit a little better in this car after a seat mod to bring it back a little further. But yet i miss my STI SOOO MUCH!!!!
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post #8 of 8 Old 07-13-2011, 08:33 PM
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I have this problem too on a 04 STI and with this I was able to notice a damage cable.

http://img3.imageshack.us/img3/9066/imag0306wi.jpg

Quote:
Originally Posted by freshmro View Post
So I too got the mysterious P0447 cel. Doing some reading I narrowed down the real problem and this is what I came up with. I have a 2002 WRX with 105k miles.

Background:
First off while there probably are some gas cap issues or leaking gas lines I believe that the majority of these faults are caused by bad wiring. This cel refers to a solenoid valve to check the fuel lines for leaks. I have read that it is only used when the car is first started up. From what I can gather it closes the valve checks a pressure sensor and then can determine if there are any leaks in the fuel / fuel return lines. If anyone wants to correct /clarify my understanding...please enlighten me.

Location:
The location of the valve is in the rear passenger side of the vehicle. There is no need to jack up the car or remove the wheel. Just get out some trusty card board and slide you head under the rear bumper. First you'll notice a black plastic box, slightly smaller than a shoe box. it will have a few hoses connected to it. I believe this is the evap cannister. Next to this box is a wire harness with a connector that is connected to the solenoid valve in question.


Inspection:
First thing to try is remove the connector from the solenoid valve and clean out all the crud in there. With the connector disconnected start the car. The connector hangs down enough to access it with a volt meter. Set the meter to VDC and measure the two pins in the connector. If everything is ok you should read 12v. I measured 0.47vdc when i checked. If you have 12v you most likely have a problem somewhere else and my advice won't help. How ever, if you read anthing other than 12v you have a problem.
TURN OFF THE CAR!!

Next slide back under the car with some liquid wrench and a 12mm socket with extension. Remember the black shoebox thing, there should be 3 12mm nuts holding it to the car. Two in the back and one in the front. Be careful when removing them because they are mounted to soft rubber/plastic dampening thingies.

The black box will drop down out of the way. Be careful not to flex the hoses too much. With the cannister removed the rest of the solenoid valve harness is exposed. You'll probably notice rust/dirt/crud hidden behind the box. I beleive this is because this area is not shielded from the rear tire and all kinds of slop gets thrown in this area.

Follow the harness from the solenoid valve connector up untill you get to a "Y" in the harness. You'll need to remove all the electrical tape from the connector to the "Y". Under the tape I found some split wire loom. This can be removed. (mine was completely filled with moist dirt. When the split loom is remove a solder joint will be revealed. My solder joint had failed it had turned green an the wire had broken from the joint. I don't know what clown installed this but....WRONG! It seemed to me the splash from the tire had gotten up into the wire harness and rotted out the solderjoint/wire.

I cut back the rotted wire. Stripped and tined the ends and soldered the 3 wires back together. Temporarilly I have covered them in heat shrink and electrical tape. After I got the wires soldered back together I bolted the cannister back up into the car.

I cleared the cel (I have an accessport) and started the car. EUREKA! Problem solved. I don't know if this solder hack job was done at the factory or from the dealer during a service but this is a bad location to just solder and tape. Before the winter I will be going back under there with some new split loom and some RTV and some electrical tape and try to water proof the begeezee out of it.

I'm gonna try to attach a photo of my adventure. Hope this helps.
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