I have a code P0456 "evaporative emission system (small) leak detected. I've searched the forum and see it's fairly common. I have an '04 with over 300k miles. Already tried replacing the gas cap. Many of my vacuum lines are dry and brittle. I'm hoping there is a cracked line somewhere causing the code, and nothing from the exhaust. I see many different size hoses. I've already changed out the hose that originates at the PCV valve.

If I recall, another member changed out all of their hoses and listed the P/N's. I can't find this thread. And if anyone has used aftermarket bulk hose instead, please share what sizes and where you purchased it from.

Also, for those that have changed out their vacuum lines, how did you get to the 2 lines located below the power steering reservoir? Even with removal of the 2 reservoir hoses, I can't see how to get a pliers/screwdriver down there to attach a hose clamp to a replacement hose.

 

This is an uphill battle for sure because everything under the hood is metric and parts stores only sell inch diameter hose. Download an inch to metric conversion chart to help see what you can get by with. For example, 8mm is close enough to 5/16" hose you wouldn't know the difference but 10mm is close to 3/8" but trying to make it fit is quite annoying.
Many can be purchased from the dealer but sometimes the cost is very high especially when all you get is a short section of bulk hose in a Toyota package. Toyota does sell some bulk hose so you might start there and see how much you can replace that way.

 

Bradland, thank you for the reply. Or I should say ありがとうございました (thank you)!

 

Anyone else on here change their own vacuum hoses? I've hit a brick wall with the 2 hoses that run down next to the power steering reservoir. Even with the reservoir removed, I could not reach the clamps.

 

Are you sure they are vacuum? Can you post a pic..?

 

I should have specified...thanks to your diagram bradland, it's part #'s 17343B and 17342B. Definitely vacuum.

 

You’ll prob have to remove this intake plenum to get the access you need up top. Down below they are attached to the ACV (air control valve) the 2 prong device 44410 on the diagram below.

 

I remember replacing all the small vacuum hoses years ago, as they were all brittle beyond belief and useless. Got everything through Lexus....Don't remember spending a fortune and all the hoses fit properly. Lexus should provide a parts list... I changed most of the hoses including some plastic pieces as well.

 

Yes I did remove the plenum, air filter assembly and power steering reservoir, but those hoses go deep and there is no easy way to get a hand in there. Definitely can't be accessed from below either. 17343B is cracked and I'm hoping the cause of my PO456 code, although I tried sealing up the crack and hose end with silicone caulk for a temporary seal, but the code remains.