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Mike V.
Mike V., Subaru Technician
Category: Subaru
Satisfied Customers: 24035
Experience:  Certified Subaru Technician, factory trained by Subaru.
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Subaru forrester: Mike. Russell from Russell Auto in Cambridge

Customer Question

Hi Mike. Russell from Russell Auto in Cambridge ON. We had a previous code that was for vent solenoid stuck open so replaced with prt # ***** The car was filling fine before and after the repair. customer complained that the light came on again and she couldnt get gas in. We had a code p0435 set, pressure sensor switch high, We replaced this sensor from Subaru, prt # ***** The custome called a week later and light on and could not fill again. Same code and cannot fill again. We disdonnected the solenoid out of the system so she could go on her trip. Shes back and now we have to figure this out. We checked all the components and they all seem fine. ANY direction you could give us would be a big help. If there is a charge just let me know how you do it. Thanks in advanced. Russell
Submitted: 1 year ago.
Category: Subaru
Expert:  Mike V. replied 1 year ago.
Hi there,Do you have a code set again or just the issue with not filling?
Customer: replied 1 year ago.
code is set again
Expert:  Mike V. replied 1 year ago.
Ok, I am thinking you mistyped the code as I am showing a 453.Will your scan tool read the FTPS? If it will, check the voltage with it plugged in, then with it unplugged just to make sure there is a difference. Since it looks like the vcv isn't opening it likely does have to much pressure in there.If you locate the green D check connector under the passenger side of the dash and plug it in, you should be able to connect it then turn the key on. Once you do this the check engine light will flash and the fans should run. This will also set all the solenoids to turning on and off. As you hear them clicking, go back to the vent control valve and make sure it's working. If not, unplug it and use a test light, one wire should always show a constant 12 volt, and the other should go to ground, so reverse the test light and see if it flashes to ground or when that one is suppose to ground. This will basically check the wiring from the computer all the way to the vent control valve.Try this and let me know the outcome.
Customer: replied 1 year ago.
My tech will do this shortly and will let you know the resaults
Expert:  Mike V. replied 1 year ago.
Sounds good Russell, we can work on it from there. Figured it's enough info to get the ball rolling the right direction at any rate!
Customer: replied 1 year ago.
We operated the valves and they are both working with the computer driving them. The inability to fuel we assume the vent should be open the atmosphere? With the car off and everything hook up, there is air movement. When we join the 2 lines together she has no issue filling the vehicle. We could be misunderstanding and that there is somewhere else it vents to? There is a shut valve on the side of the filler neck that we would need to pull things apart to get at, could this be an issue?
My tech is leaving for the day. I will have to bring the car back to continue. I will talk to the customer and find out when she can do that. Will mail you with you when we are going to do that.
Expert:  Mike V. replied 1 year ago.
Typically what happens is the canister becomes full of fuel vapors when the canister vent isn't working. If the computer is commanding it to open when the purge happens it should clean that out. Basically it's closed most of the time, but when the pressure gets to high, then it should open and the purge solenoid should allow manifold vacuum to pull the fuel vapors out of the canister. So, i would next focus on the purge solenoid to make sure it's opening when it should. I haven't seen to many issues with the shut valve in the fill tube, so I think we need to know it's pulling vacuum as the next step and sucking the vapors out of the canister.Based on what the pressure sensor is telling us, this isn't happening and eventually there is to much pressure in there preventing her from filling the fuel tank.Please let me know when you can.What happens next:Just Answer will now charge you for the full amount of your question.My goal is to provide you with 5-star service. If you cannot rate me at least 3-5 stars, we will keep working on this.Just Answer does not compensate me for my time and effort; you do with a 3-5 star rating.Follow up questions are included in your question price even after rating.
Customer: replied 1 year ago.
Morning Mike. Russell here. We have this Forester back today. We forgot where we stand. We know the computer is commanding the solenoid open and I think that's where we left off?
Customer: replied 1 year ago.
If you want we can commune through my email. Its***@******.***
Expert:  Mike V. replied 1 year ago.
Morning Russell,I think you need to put a scan tool on the car and see if you can read the pressure sensor voltage. With this type of setup it's kind of a pain because in the old style you had a return line and you could run the car and as the fuel heated up you could see a pressure change. With this style you literally need to take a reading from the pressure sensor and then park the car in the sun, go back an hour later and take another reading. This is to make sure the sensor is actually working. If the sensor is working there will be a voltage change that you should be able to see on the scan tool. If the sensor is working then I would focus on the purge solenoid. If the solenoid isn't working then it won't pull the vapors from the canister and eventually that will fill up and you won't be able to pump fuel into the car, the vapors won't have any place to go.Please check this and let me know.I can't really communicate through email with this because it's against JA policy.
Customer: replied 1 year ago.
In progress Mike
Expert:  Mike V. replied 1 year ago.
Sounds good, hopefully we can get this sorted out!
Customer: replied 1 year ago.
Hi mike. We are looking at the PRESSURE SENSOR right now. There are 2 hoses to it. 1 to the tank, the other seems to just hang there. Is this normal?
Expert:  Mike V. replied 1 year ago.
I believe this is normal. This is usually going into a void in the frame and not attached to anything.
Customer: replied 1 year ago.
Thanks. Still working on the sensor
Expert:  Mike V. replied 1 year ago.
I have an idea that might help. Take the sensor and use a vac pump on the hose and watch the voltage on the scan tool as you add pressure or vacuum manually and see if it's changing. If it is, then we know the computer is seeing signal from the sensor and the sensor should be working.
Customer: replied 1 year ago.
Hi Mike. The green connector under the dash. You said its the test connector? It was plugged in all this time. Should it be plugged in when everything is normal and the car is running down the road? Also, when we plugged it in the scanner says its NOT plugged in and the solenoids do not switch.....
Expert:  Mike V. replied 1 year ago.
The D check connector should NOT be plugged in when the car is in normal use. It's a test connector and they have it plugged in when shipping the cars, otherwise it should not normally be plugged in.
Customer: replied 1 year ago.
Hi again. This car was in at the dealer a year ago for the light being on and the customer does not remember what they said. She is looking it up. The sensor reading sits at 1.881 and goes to 1.875 mercury at full vacuum according to the scanner. When you unplug the sensor the number doesn't change. The multi-meter voltage is 2.5V and goes up and down with vacuum. Maybe we should we ignore the scanner and rely on the multi-meter? .
Expert:  Mike V. replied 1 year ago.
See if you can back probe the connector and check it with the meter while it is plugged in. See, what the scanner is telling you is what the computer is seeing. Since it's not changing the computer is not turning on the purge here is what I am thinking. If you can back probe the harness connector and get a reading then we might have to be checking the computer pins next.
Customer: replied 1 year ago.
My tech is thinking the same, but, what about this. We put EVERYTHING together again, leave the test connector disconnected and drive the vehicle ????
Expert:  Mike V. replied 1 year ago.
Try it, the important thing is to keep an eye on the pressure sensor voltage. We need to see some kind of decent voltage change in there.
Customer: replied 1 year ago.
The voltage with the multi- meter was at least 3 volt movement. and that was only using our breath. put everything back and have driven it to gas station. Put 5 bucks in real easy> then I went for a drive as well> not we are going to let it sit for 20 minutes before driving again. He has a oil change to do
Expert:  Mike V. replied 1 year ago.
Sounds good, I really would like to know what shows up as far as the voltage you are seeing with the scan tool. Then see, if it's different then what you see on the volt meter, we go to the computer and check the wires at the computer. If the same voltage shows up on those wires with the meter, but not in the computer, the computer is no good. If the voltage you are seeing on the scan tool shows on the wires at the computer, then you have some corrosion someplace in the wiring and are losing the voltage there.
Customer: replied 1 year ago.
Our Snap-On scan tool shows mercury values, not voltage. We have Canada day coming up so I have to get her back in the car now. We are putting all the covers back on she I can go get her. Could them leaving that connector plugged in cause damaged?
Expert:  Mike V. replied 1 year ago.
Won't cause damage, but will cause several false codes. Let's hope that unpluging it will make a differenceEnjoy your Holiday and please remember to rate at some point if you haven't already!
Customer: replied 1 year ago.
Thanks. She'll be back next Monday and let us know. Thanks. I will send as soon as I know
Expert:  Mike V. replied 1 year ago.
Sounds good!

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