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2004 Forester XT 4EAT
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Discussion Starter · #1 ·
I have a 2004 Impreza TS (same as '99-'04 Forester) that had the Check Engine LIght (CEL) on for a P1443 - " EVAP Control System Vent Control Function Problem ".

The fix was to replace Purge Valve control solenoid, P/N: 16102AA080 (16102AA490 for '05-'07) - located under the intake manifold on the passenger side of the engine. This part is the same as on a '97 Legacy that I recently had, so it's a common part that Subaru has used for years. And due to the cost, would be worth trying a used one (if you can return it). New runs $90+.


This didn't cause the car to run/drive any differently but it did have a related side-effect: When refilling the fuel tank, the car would stumble / Idle poorly / fail to start on the 1st try. This only lasted for 30 seconds and the car started and ran fine otherwise. I did NOT have the refueling issue that causes the fuel pump to turn off prematurely, which seemed to come up more often with the P1443 code (see attached for diagnosing that issue.)

If you get the code, use the Diagnostic tests attached FIRST before spending a dime. Basically, w/the key off, connect the green connectors under the driver's side of the dash, key to ON >>>engine OFF, and ensure all the solenoids involved are clicking and airflow isn't continuous while clicking...the valve should open/close causing the airflow to be interrupted.

History (but not a recommended troubleshooting sequence!):

I spoke to a Subaru parts supplier that I've used for the last few years and he suggested, after talking to a tech, to replace the Canister Vent Valve also known as the Drain Valve, P/N: 42084FA120. This is in the back behind the passenger rear wheel underneath the car for the 1999-2004 Subaru Impreza (includes the WRX and STi) and Forester. I think it's the same for Legacy and Outback. (Based on other threads, the Canister Vent/Drain valve was integrated into the charcoal canister on '05+ models.)

This is a pic of the parts in the EVAP system. The Canister vent valve solenoid/Drain Valve (top of pic next to the cylindrical drain filter) and the pressure control solenoid on the lower right located in back of the car, the Charcoal Canister (underneath everything) and the purge valve control solenoid (the separate part w/the hose) from the intake manifold. See attached.

After this had no effect I replaced the Charcoal Canister and cleaned out the Drain Filter. This was also a no go.

For reference the charcoal canister weighs less than 3 lbs. when new but when diagnosing issues, many techs will replace it if it weighs 4-5 lbs.. Also, if you have a habit of 'topping off' - STOP IT - you're likely back feeding fuel into places it's not supposed to go - such as the charcoal canister.

Finally, I got my act together and found a document online and was given one by the Subaru parts dealer (see attached) that recommended using the green diagnostic connectors under the dash (Video
). This cycles all the solenoids, radiator fans, etc on/off to verify that they are @ least getting power.

Also Fairtax4me on the USMB site gave me the following good info:


the Drain valve (canister vent valve) is the valve referenced by this code.

The drain valve solenoid is closed by the ECU at certain times, to diagnose leaks in the evap system. It looks like its supposed to be open normally to allow fresh air to enter and exit the canister.
Use the test mode plugs to check the drain valve for operation. It should click on and off in roughly one second intervals. If it doesn't click check for battery voltage reaching the plug. Then check the other pin in the plug for continuity to ground. It should fluctuate between ground and no ground as the ECU toggles the ground side of the circuit.

If it clicks, try to blow air through the valve while in test mode to make sure the valve seals properly.


You may also have a problem with the purge control solenoid under the intake manifold sticking open <this WAS MY ISSUE!!>. If the purge solenoid sticks open it draws vacuum on the canister all the time when the engine is running. It also allows fuel vapors from refueling to enter the engine right after starting, which makes the fuel mixture too rich. It basically floods the engine, which could cause it to stall. If the engine is warm the O2 sensors pick up on this and the ECU then adjusts the fuel mixture way lean to try to compensate, which could also cause it to stall.
Blow air through the purge solenoid while in test mode to make sure it seals properly. If it doesn't seal properly you can try blowing some compressed air through the ports to dislodge any crud that may be in the valve. Some of the purge valves you can disassemble and clean the valve seat and the bore it sits in.
I checked that the two in the back - Canister vent valve solenoid/Drain Valve and Pressure Control Solenoid, and then the Purge Valve Control Solenoid @ the intake manifold. The Purge valve wasn't cycling and when I blew thru it, air was able to flow continuously....it was stuck OPEN.

I swapped in an extra Purge Valve I had and tested it. As well as cycling on/off, it also turned the air flow on/off as i blew thru it......problem found! I drove the car for 30 minutes and the CEL stayed off, whereas before it would come on w/in 5-10 minutes of cruising on the freeway AND when I put in some fuel it started and ran fine. I'm calling it FIXED....after much frustration.

Here's a pic of the Purge Valve disassembled. I can't see anything wrong w/it, but some have indicated they might be able to be fixed???:



 

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Good info , went thru this about month ago , went to wreckers pulled 1 off another Forester mystery solved , Emission problems are annoying and tricky ,when you are looking for a pin hole .020 of an inch. without a smoke and dye pump.
 

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2001 Forester auto
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Excellent write up, thank you. I have a 2001 Forester that was pulling the same code P1443 and had the same issue after getting fuel, car would start rough and stumble for a minute. I took everything apart back by the canister, ran the diagnostics and found all solenoids operating, used my compressor and blew air though all the lines and the vent and found no leaks or clogs anywhere. I was scratching my head wondering what it could be when I found your post here. My Purge Valve control solenoid (buried under the passenger side intake manifold)was firing when running the diagnostics and quite frankly it looked like a real PIA to take out so I first did what you mentioned about checking the air flow when in diagnostic mode, I disconnected(at the manifold not at the valve) the one line that comes out of the Purge Valve and runs over the top of the manifold to a threaded nipple, no need to undo the nipple just pull the rubber line off. I was able to blow through the line while the valve was cycling and could tell it was not closing fully. So I ran my compressor up to 40 psi only and carefully blew that into the line while in diagnostic mode. I could tell right away that it freed up the valve as the line actually vibrated when the valve cycled and air flow was restricted. Took the car for a good ride and the code is gone. I have no idea how long the valve will remain free and keep functioning but at least I now know what to part to buy and replace if it craps out again and the code comes back.
Thanks again, made my day !
 

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2004 Forester X 4EAT
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Thanks for the write up! A couple weeks ago my 04 Forester X popped the P1443 CEL out of nowhere while coming back from Tahoe. I pulled over, examined the car and cleared the code... came back on after about another 20 miles! Next time I went to get gas I also had the issue of stumbling, idling poorly & failing to start on the 1st try.

My research at first led me to believe it was the evap vent solenoid. Went to pick n pull and found an 01 Forester w/ 160,xxx to pull a vent solenoid off of. My 04 is at 248,xxx so I figured with that many less miles on the 01 I had a good chance of getting a solenoid that was ok. Changed the solenoid and reset the ecu, was able to drive >220 miles and the CEL never came back. Great right? Wrong. Turns out that despite the CEL not coming back I continued to have the rough starting issue after getting gas as well as the evap OBDII monitor never obtaining a 'complete/done' state.

I made another trip back to pick n pull today and got the purge valve control solenoid off the same 01 Forester I visited the first time. Swapped in the new solenoid about 20 min ago, so with some more driving I'll have to see if this finally fixed the rough start after fueling issue & evap monitor.

One thing to note is that my old purge solenoid (while off the car) I was able to blow air through it while the 'new/er' one I got I was unable to do that... leading me to believe the old one was letting fuel vapors from the tank enter the engine causing an extreme rich condition.

I'll make sure to post back tomorrow with an update! *crossing fingers*
 

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UPDATE:

I can now 100% confirm the cause of the rough startup after fueling was the purge valve control solenoid.

Filled up from a 1/4 tank to almost 3/4, turned the key and it started up perfectly!

Also ended up driving upwards of 50 miles tonight so I rechecked the evap monitor and it did obtain a complete/done state.

Very happy this is over now however I'm still puzzled why replacing the vent solenoid near the charcoal canister caused my CEL to go away despite that the old one I removed seemed to function just fine.
 

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2003 Forester 2.5 XS MT
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Hello,

Mine is Forester 2003 XS;

Shown codes on OBD: P1443 and P0447;

I removed pressure control solenoid valve (shown on image) and checked it with direct voltage 12v and it works - close/open;

535561


So can it be any other sensor ?

Thank you;
 

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Discussion Starter · #8 ·
@MyForic2003 Please read my 1st post...plug in the GREEN diagnostic connectors under the dash and check the Purge Valve control solenoid under hood.
 

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2003 Forester 2.5 XS MT
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Hello,

I checked with green connector test and both back and front(under the hood) solenoids works mechanically - they has sound during test.

So, now I have to dissassambly Purge Valve which is under the hood and check machanically ?

Thank you.
 

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Discussion Starter · #10 ·
What are your symptoms - besides the codes? Hard start? Unable to fill the tank? etc.
 

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2003 Forester 2.5 XS MT
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@wtdash Absolutelly no any differece in behaviour then before this CEL lighted;
Not tried to fill tank yet, but added fuel several times - to 45-50 litres

Btw. today I uses my OBD ScanGauge to clear codes considering, that it will clear and then show again after Scan,
but as a result CEL also dissapered and during 10 minutes driving not appers anymore - no CEL, no Codes;

can I guess that it was some temporary issue or starting of some future issue ?
 
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