P0446 - Evap Emission Control System Vent Circuit Malf

Been getting this code lately. Ive cleared it several times and it usually comes on at start up (during the egr test im assuming). Although its not faulting 100% of the time.

Any insight or ideas? I'm at 68k so no warranty for it. Ive checked the charcoal canister, all egr hoses, wires, and my fuel tank cap....all to no avail.

 

bump

 

.......

 

I have been getting this same code on my DD Celica...The research I did, lead to a servo type motor located near the fill neck (on the celica) that controls vapors coming back from the engine...or something to that effect. I haven't yet looked at it though...Ironically it's the same P0446 code....stupid emissions bs.

 

well guess im just going to disable the test in ecuflash.

 

the computer will do a system check on start up and apply vacuum to the gas tank and then monitor the sensor on the gas tank. if it hold vacuum then there no leak, if it doesnt hold vacuum then it'll kick on the check engine light. it have nothing to do with the egr system.

 

well what should i check to start with i looked at all the lines for the charcoal canister, check the fuel cap. not really sure where to go on this.

 

P0446 usually is a venting problem not a leak. There should be Vaccum switching valve (VSV) on the Charcoal canister that controls this.
Either the valve is stuck open or close or even not getting the command to operate.
A good scan tool (expensive) with an ACTIVE TEST mode for VSV can perform these checks.
Or just rig a power source (12v) to the VSV connector and see if it clicks.

Check your hoses if their loose or maybe came off prior to going futher through the diagnosis.

 

Thanks Nad....Yeah I read about it and doing this 12v test. Is the VSV on the right side of the canister?

I checked all the hoses, everything looked good...Do any of these hoses run forward or is all to do with the fuel tank? Did you have this issue on your lexus? seems like when i google P0446 most of the stuff that comes up is Toyota and Lexus posts, mainly toyota though.

 

vacuum switching valve(VSV) is what toyota call them. it is a solenoid that open or close when voltage is apply to it, so it can apply vacuum or cut off vacuum to certain component. toyota use it to control many thing that uses vacuum.(like egr valve and etc..). look under the hood and see if you can find the sticker with a diagram of the engine vacuum rout and emission components. make sure the solenoid in the engine bay work. when you apply power and ground to it, it should click. mitsubishi and chrysler use the same evap system and most of the time is the leak detected pump that go bad. hope this help

 

So I've check resistance thru the solenoid (one mounted inboard of the charcoal canister) and it was within spec 17 ohms and the power supply was 12.4v

Any other ideas? I'm trying to find a good solenoid to just replace it with and see if that works. Trying to see if I'm overlooking something here.

 

Did you check the VSV located on the Intake manifold support bracket (under your intake) to make sure that the vacuum hose (vent hose) is not kinked and that the VSV is actually working as it is part of your Evap system.

 

I've checked the hose, however I haven't tested it. Is the test the same checking resistance? Or should I send power to it to see if it works?

 

Yes,give it 12 volts as you want to make sure it operates. You could even hook a vacuum pump to hose that goes TO vsv and put system in vacuum and then power up VSV and and see if vacuum drops right off and if it does you may have another problem,possibly a hairline crack in your charcoal canister and sometimes that can only be found with a "smoke" machine. I have not seen many emissions trouble codes on Mitsu but I formerly worked for Toyota for a Looonnnngggg time and have seen my share,mostly due to the location of the evap vsv and lack of any type of protection for it from road salt and such.

 

How will I know it operates...guess I'll find out if it at least does something lol. Yeah it seems like Toyota had lots of issues, I couldnt find any mitsi info all Toyota/Lexus posts.

Thanks for the response turboDan!