When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
2001 LS430 overfill check valve: go through the floor?
I suspect my P0440 and lack of pressure in the gas tank is due to a cracked overfill check valve as I've seen people experience in other models. (A new gas cap did not help.) I'm planning to take it to the shop for a smoke test and to rule out other causes like a bad hose, but if my suspicion is correct, would rather not have to pay what it would likely cost to have the shop replace the valve the "right" way by dropping the tank. Nor do I really want to face doing that myself.
I've seen where some people have replaced the valve by going through the floor, but only on different models. For example, this thread. Has anybody here done that on a 2001-ish LS430? Looking for advice on feasibility, exact valve location, and technique.
What I have to go on so far is photos of the procedure on other models, plus a page from the shop manual showing the valve's location on the tank, and a shot I took of the rear floor of my car (my guess as to valve location is highlighted).
I don't think it's that but could be wrong, so thanks for bringing up that possibility. There are several other things it could be too, and hopefully a smoke test will point the way.
I replaced the valve on my old IS by cutting thru bottom of rear seat using sheet metal shears....I did not see anything wrong with the old valve after replacing. Seems like it was a loose hose.
Did you ever decide to go through the floor? I’m getting ready to cut an access hatch and I was wondering if you ever found the placement of the check valve. This seems to be the only thread about replacement on an LS430.
I was never able to convince myself that I knew exactly where to cut, so in the end I chickened out on replacing the valve myself. Found an independent Lexus shop that did it the right way for (I think it was) about $600.
Well, after some thought I decided to go through the floor. I drilled a hole near the spot you marked and when I shined a flashlight inside I confirmed that you were actually spot on ..lol. After cutting a hatch, I peeled it back and then replacing the original valve was a breeze. The manual reccomends using a trim puller to lift it out of place:
Removing the old check valve revealed that it had cracked around the top edge (Cause for lack of pressure in the gas tank) and the hose running to the canister seemed to have some small cracks. It can’t be removed, so I trimmed the end and that seemed to fix it. After installing the new valve, I hammered the hatch back into shape and closed everything up with aluminum tape.
The codes I had experienced before (P0440, 441, 446) are gone and have not returned. The gas tank goes whoosh when I open the cap. Now I can finally pass emissions! Hope this helps anyone with a 430 who is having the same problem with these codes after replacing everything in the vacuum system.
Nice write up. Just an FYI to anyone else following along, you can pass emissions without actually fixing anything if your only codes are EVAP related. Fill the gas tank, reset the codes, drive around until all the other monitors run, and then get your emissions test before the fuel level goes below 3/4.
08-24-20, 08:52 AM
2001 LS430 overfill check valve: go through the floor?
