p0446, p0441, p0442 fixes?

that's good info there. thanks

 

ok after I replaced the gas cap I am no longer getting the 446 but still getting the 442 and 441. Did the VSV checks under the hood and found the Vacuum VSV bad. The ohm checked out fine but the blowing the air with and without power failed. The good VSV made a nice motorized sound when I applied power to it and closed like it was suppose to. The Vacuum one didn't do anything. I did noticed that only that VSV had rusted clamps on them and nothing else does. Might have water damage? I ordered a new VSV for $68 shipped.
Cross your fingers and hope it works!

 

yep $57 for the part and $10.50 shipping. Denso

$55 25860-75230 Vapor Canister Purge Solenoid

25860-75230

 

OK!!!! changed the VSV today and guess what? I now have pressure in my fuel tank! I drove it around the block. Stopped the engine. Pulled the fuel cap and there was the hissing that I have missed hearing for so long!!!!!!

 

An informative thread; lots to check out as time permits. So I'm getting the same set of codes. Sometimes just P0441, sometimes P0441 and P0442 (most of the time), and once I got P0441, P0442 and P0446. The gas cap was replaced a couple of weeks ago and I get the hiss when I remove the cap, but the codes came back. Also to note, the CEL and trouble code alarm (from my Ultragauge) came on about midway in my commute to work. No heavy load or acceleration - just normal cruising if that helps.

So after reading the thread and a few of the imbedded links, I'm thinking that P0446 is something to check into last (seems that this code could be thrown as a symptom of another issue related to the other two codes). When I got a printout of the codes from Autozone a couple of weeks back, it noted that the gas cap was the primary culprit and a couple of other items (I forget what they are at the moment). Well, gas cap was replaced, but this did not resolve the issue. It is an aftermarket replacement, but as I noted earlier, the 'hiss' is there when you remove the cap, so I think it's functioning correctly.

Any kneejerk thoughts on what direction to go? Evap VSV, one of the other VSVs, or the cansiter? I also understand that there is a smoke test that can be run to ascertain if there is a leak along the system. Has anyone done this and is this a good place to start? But if there were a leak, would I get the 'hiss' when removing the cap?

Thanks,

Kevin

 

So I went back to the used car dealer I bought the truck from and this is the outcome:

New cap: it wasn't the cap.
New filler tube: it wasn't the filler tube.
New cannister with new valves on as an OEM assembly: not that either.
New VSV brelandt used to fix his problem: that did the trick!

The funny thing of it was that I mentioned that I read here online about the VSV and tossed that out there as a possibility to help with the diagnosis. The dealer could have saved himself time and money had he listened. And I would have been driving without the CEL for months while he tried to figure it out.

 

The P0446 code should have been your first indicator that the VSV valve was most likely the cause. P0446 is a code that indicates a circuit problem with the VSV. Usually this is due to a VSV that is internally failing, and not closing. this prevents the EVAP system from creating a vacuum in the system. This is further supported by the other two codes which indicate both a small leak, and a large leak detected. (a intermittent VSV valve can cause a partial, or no closing at all. This explains the two different leak codes.

Just some information to help in case others are looking at similar codes.

 

Correct diagnosis Bill. The mechanic speculated that something was keeping the valve from closing, perhaps pulling something up from the cannister. What curious is that I suggested the VSV but nobody checked that out first. Would have saved everyone time and them money. Got tight in the end as I needed to do the emissions - passed without any problems and truck is running fine.

 

Had the evap code on my 2000 Tacoma V6 4x4 found this simple fix.

https://www.youtube.com/watch?v=IUHo_nQgDxM

Charcoal box was cracked on the bottom corner. On my truck the charcoal box is in the engine compartment.