So I bought my evo last June. The day after I got home it threw the SES light.
I went to the local auto zone and had the codes ran. It was throwing the p0455 and p0456. I changed the gas cap had the code cleared.
2 days went by and boom it's back. So I have been dealing with looking at it now for a while and finally decided to try and take care of it today. I made a special gas cap with a valve stem in it so I could put air in the tank and find the leak. Well I found the air comming from the white fitting that goes into the frame at the back of the car. So that being said I figured the evaporate vent selinoid must have malfuntioned. I removed the whole evap junk from the back of the car and got to the selinoid. When removed I could blow through it. So for a matter of testing I allpied 12v to the selinoid and it sealed up.. So that's when I took the selinoid and just plugged it into the cars wiring to see if it was being energized by the car. I got nothing. I started the car and I couldn't get it to close off. I'm out of ideas. Any input would be great. Anyone have similar issues. Is there a certain sensor that would cause that to not close up?
Thanks
Rob

 

if you don't have access to a smoke machine, it's very hard to find a leak on the evap system, unless it's obvious like damage to the canister or a hose popped off. take it to the dealer or somewhere they can put some smoke in it. i've seen everything from a fuel tank pressure sensor bad or leaking, to the actual filler neck leaking. you need a diag or youll be chasing it for a while. good luck.

 

well thats the thing, i have found the leak, and its because the vent solenoid isn't closing, so i just need to know if there is a sensor that wont allow it to go closed if the sensor is failed. i have closed off the vent that goes to the canister and there isn't any leaks. so it has something to do with that dang solenoid not getting the 12v to close..

 

the vent solenoid is normally open and closes when pcm checks for leaks. your leak is something else.