I have a 2008 Sienna LE with the P0441 and a P0455 code. I can't find any cracked hoses or missing hose clamps. Using my Innova 5610 scan tool I have run active VSV tests. When I activate the VSV for Evap Control, I hear the module click. When I activate the VSV for Vent Valve I don't hear anything. When I use alligator clips to directly power the purge solenoid, it clicks. Both EFI fuses appear good. Can anybody tell me what to check next? Any likely places to check for known issues?
chrisv011
Just so I know that I am checking the correct parts, pic_1 part I'm hearing a click and pic_2 part no click during the active test. The vent valve (pic_2) does click when I power it directly from the battery.
Attachments
Do you get only the CEL or also a flashing low fuel light? I'm not one to suggest the parts cannon but for a large leak (P0455) a new genuine Toyota fuel cap after 17 years isn't unreasonable.
Does the second picture show the vent control valve? IIRC the vent control valve is at the evap canister by the fuel tank. Second picture looks like the air intake selector for the air cleaner in a 2004-06 3MZ. Your 2GR might be different.
VSV clicking is half the test. Also have to confirm the valve doesn't leak when closed. There's a lot of evap plumbing to check around the fuel tank and to the engine bay. Push comes to shove, smoke testing is your friend. You'll need a pressurized smoke source for the extensive plumbing of the evap system.
Sixto
04 LE FWD 240k miles
Does the second picture show the vent control valve? IIRC the vent control valve is at the evap canister by the fuel tank. Second picture looks like the air intake selector for the air cleaner in a 2004-06 3MZ. Your 2GR might be different.
VSV clicking is half the test. Also have to confirm the valve doesn't leak when closed. There's a lot of evap plumbing to check around the fuel tank and to the engine bay. Push comes to shove, smoke testing is your friend. You'll need a pressurized smoke source for the extensive plumbing of the evap system.
Sixto
04 LE FWD 240k miles
I always get the P0455 with a P0441. I have put new gas caps on twice. Yes, Pic 2 is the Toyota 25860-0A010 Vacuum Switching Valve Assembly. Isn't that what should be clicking when I activate the VSV for Vent Valve active test? I don't hear anything by the vapor canister either. Should I? As far as I can tell all of the evap valves are in the engine compartment, but I am no expert. I have been fighting this problem for a few years and techs tell me there is nothing wrong. Should smoke testing be my next step?
This is a Sienna charcoal canister the evap system draws from:
![Image]()
![Image]()
IIRC the vent valve is the round thing on the upper left, the vent valve VSV is contained in the leak detection pump, the ovate thing with wires.
For grins, remove the intake snorkel above the radiator. It's held by two 10mm headed bolts. It'll reveal two paths to the air cleaner - an upper path and a lower path. That VSV actuates a flap ahead of the air cleaner that selects air from the upper of lower path. I think it's a sound control measure. Some folks swear disabling the flap nets 5-10hp along with intake noise during hard acceleration. Has nothing to do with evap system.
Sixto
04 LE FWD 240k miles
IIRC the vent valve is the round thing on the upper left, the vent valve VSV is contained in the leak detection pump, the ovate thing with wires.
For grins, remove the intake snorkel above the radiator. It's held by two 10mm headed bolts. It'll reveal two paths to the air cleaner - an upper path and a lower path. That VSV actuates a flap ahead of the air cleaner that selects air from the upper of lower path. I think it's a sound control measure. Some folks swear disabling the flap nets 5-10hp along with intake noise during hard acceleration. Has nothing to do with evap system.
Sixto
04 LE FWD 240k miles
The VSV in the 2008 is in the engine compartment as far as I can tell. The pump is all that is attached to the canister. My conclusion is that the VSV that I replaced 2 years ago is already bad (cheap Amazon part), so paid more for an O'Reilly part. Also used clamps to snug the hoses. Hopefully the code will not reappear.
The codes came back. I ran the key-off evap test using my scan tool. The results are attached and I need some help interpreting the results. I'm guessing that 14 PSI is too high? While the pressure does drop during certain parts of the test, I have no idea what each step means diagnostically. Do I have a leak or a blocked line? Is a smoke test going to help me figure it out?
To recap...the gas cap has been replaced and the purge solenoid (Pic_1.jpg from above) has been replaced. I'm having trouble figuring out where the "vent valve" is located. The vacuum pump on the vapor cannister is all one piece and I can't find a part number for anything cannister related except for the vacuum pump. Where is the "vent valve" on the 2008? What does it look like and where can I buy a new one?
Did a smoke test and didn't find any leaks. Also just figured out that the leak detection pump on the 2008 Sienna vapor canister ALSO includes the fuel pressure sensor and the vent valve. Changing the leak detection pump assembly next.
SOLVED! The P0455 code came back after changing the leak detection pump. The last smoke test I conducted through the gas fill, so I did another from the purge valve hose. Pretty quickly I saw smoke coming from under the van. I put it up and took off the skid cover to expose the vapor canister that was replaced in 2021 (started this mess!). I pulled it down to see the top-side of the canister. It had been GLUED and it was not visible without removing the part. I assumed that this local shop (that enjoys some degree of popularity) installed a new part. Instead they gave me something broken with a bad repair. At least I finally found my big leak. Thanks for everybody's help over the years.
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