P0456 code

[-=Lobstah=-]

I had a CEL come on a while ago, it stayed on for about 2 days and disappeared (hasnt come on since). So i took the car to a friend of mine today and OBDII pulled only one code P0456 (EVAP emission system malf., also it said it could be a minor vacuum leak). Any idea?

And there a strange thing about my car, i'd be driving with steady speed for a little while and when i suddenly put more pressure on gas it dosnt pick up any speed but instead i can feel some vibration on the gas pedal, it doesn't happen when i apply steady pressure though. Im not sure if the two are commected in any way...

What do you guys think?

 

[rallyXcramps]

These two symptoms may or may not be related. It'd be hard to speculate on either without looking at the car in person. Didn't you just get that at Rowe? Bring it back and tell them you have a state inspection failure (1) (check engine light) related item that needs to be fixed! And tell them you have a driveability problem (2) the hestitation.

For the code- P0456

Inspect your gas cap, filler neck all the way to the tank, make sure the EVAP canister isn't saturated, make sure all vacuum lines are in good conditon and are attached, make sure the purge solenoids are plugged in, and no vacuum leaks near the engine, make sure gas isn't leaking from the fuel pump o-ring.

I've found out the Subaru EVAP systems are way more complex and have less computer control than other brands. Others can be sealed using the scan tool and have nitrogen or inert smoke introduced to the system to find leaks. Subarus cant be sealed, making troubleshooting very difficult. Worse comes to worse bring it to Evergreen for some diagnotics. But if the code was stored in history and the check engine light is out then whatever problem it saw before isn't a problem to it anymore, for now.

 

[-=Lobstah=-]

CEL came on again today. Same code. No idea what it is. Where's a evap carbon canister on RS located?

 

[rallyXcramps]

Just behind the right rear wheel, inbetween the wheel and the bumper. Maybe check your filler neck/tube while you're in that general direction. Remove the wheel, remove the shield, clean, check of cracks and rust hole, clean, saturate it with PB Blaster (to prevent anymore rust), re-assemble.

 

[rallyXcramps]

I bet that's the code mine will throw tomorrow at inspection.

 

[rallyXcramps]

Haven't run into that situation, But I suppose you could just splice the wires back together or dig back to where the wires are good and splice in new wires to the plug. The vent solenoid is a low amperage deal so anything will probably work.

 

[rallyXcramps]

Come on woman! You dont need no stinkin diagrams. Just unbolt the box, let all the dirt fall into your hair, and find the wires on top there. You can do it! You dont need Allendata or Allmoody!

;D

Damn, now I'm curious as to whats up there too. Maybe I'll take a peek once its light out.

 

[Rightseat]

inksi, thankx for tips on chasing this code

have had CEL on since I rebuilt me motor, have same one

replaced purge valve solnoid after breaking one of the vac line fittings, CEL still brite ???

triply quattro checked vac llines, they OK

need to make sure purge valve elec fittings tight

also check wiring in rear wheel well

today am putting on CAI I bought from 04wrxjon, while am in there will try again to solve the puzzle. maybe with all that stock air plumbing torn out, I can see what's wrong

DG

DG

 

[rallyXcramps]

I dont know very much about the Subaru systems, sorry, wish I could help more. I wish my dealer had the EVAP smoke machine. It fills the whole EVAP system with a very white inert smoke and if there are leaks you can actually see it leaking out, or you can see what solenoid isn't working because it would be leaking by it. At my previous employer we were even able to see fuel pump o-rings leaking right off the top of the gas tank which would be much easier in Subarus, just lift the access panels under the seats. sorry, runon sentance

Anyways, the "Vent Control" circuit I think would have to be something electrical, and possibly the Vent Control SOlenoid itself. I thought the vent solenoid was on the fuel filler tube itself, but as Katnip stated the wires she has that are cut lead to above the canister box, so maybe its aon top of the box. A problem with the Scooby system is that it is not a stellar performer and the Vacuum line run all thru the unibody and zigzag across shart metal object and aren't protected against regular road grime (sand and salt) very well.

I forgot to bring the book home, but if I get some energy I'll take off my RR wheel and snap some photos of the EVAP crap on the fill tube and canister business.

 

[Rightseat]

I fixed the CEL with a piece of black tape on the dashboard, it workz real well

DG

 

[4WRXter]

I fixed the CEL with a piece of black tape on the dashboard, it workz real well

DG

Somebody fixed the CEL in my car before I bought it. They took the guage cluster out and removed the CEL bulb. I need to get a replacement, just in case.

 

[-=Lobstah=-]

sorry for bumping a dead thread...

The issue is fixed...

the valve on top of the fuel filler neck was rusted. as soon as i took the shield off, whole bunch of rust came flying out. The culprit was a bunch of sand/salt thar somehow got jammed between the filler neck and the body.

2 hours, 3 beers, 2 t-shirts and some benjamins later the issue is history ;D

 

[inski]

For the code- P0456

Inspect your gas cap, filler neck all the way to the tank, make sure the EVAP canister isn't saturated, make sure all vacuum lines are in good conditon and are attached, make sure the purge solenoids are plugged in, and no vacuum leaks near the engine, make sure gas isn't leaking from the fuel pump o-ring.

Hrmmm. Someone mentioned that already.

Thanks for the update. Unfortunately this is a common problem on all older Subarus. The fuel filler necks get very rusty, the EVAP valve on the neck stops doing its thing. The only thing we can do is try to prevent it by washing the right rear wheel well as thoroughly as possible, and if the shield can be removed without bustin stuff, remove it and wash the filler neck with soap and water and rust-proof the stuff with PB Blaster or equivalant.