I've been the owner my 2001 LS430, currently with 134,000 miles for over 9 years. I will admit freely that for a number of these years I have been guilty of topping up my gas tank frequently. Of course a few years ago after realizing this was an absolute no no.... I stopped. Of course it was too late. My car has had a gas smell for as long as I can remember (never inside and only after shutting it down for a few minutes) Last year I had a thorough smoke test and replaced all the vacuum hoses I could find up front as well as the PCV, the gas cap, etc and, the gas smell persisted. Last week my check engine light came on with the PO440 code pointing to the evaporative emission control system. My indie explained how this system (being quite old) is not that easy to diagnose. He suggested going to Lexus which I did and spoke with the shop foreman. They do have the means to close certain modules and narrow things down with a smoke test and other equipment. I told him about my habitual topping up and the gas smell and he felt that more than likely the charcoal canister is saturated thus giving me the gas smell. From what I understand the canister for the LS430 comes as one part so the VSV, and pressure switching valve and purge valve etc are all part of the same unit and are not purchased separately. I've been living with this symptom for probably close to 5 years or more and the car performs flawlessly. My question is this. How long can I continue to drive my car as i have or am I at risk of causing additional damage to my car such as the catalytic converter etc? I know Lexus will take me over the coals on this one. I wish it was an easy fix but seriously doubt it. Thanks all for any feedback.

 

Getting to the charcoal canister/pcv system in the rear involves removing at least 1 axle possibly dropping the subframe I will have to double check.

You are fine to continue driving your car like that it will just have less power as well as decrease gas mileage a little with the cel on. The pcv system will not effect your cats at all, it is just there for epa regulations on more performance oriented modified cars they actual remove the pcv system to boost performance. The pcv system is a closed loop system. I would not fret about it, and as long as you dont feel like your huffing gasoline drive it till the wheels fall off lol.

The rear canister can get the valve stuck open or mud wasps mice or another animal could have made a nest which is plugging the vent valve as well.

Try filling up to only 3/4 of a tank for a while see what happens, the gas will evaporate and the canister will dry out eventually.

 

The PCV (Positive Crankcase Ventilation) system is completely separate from the Evaporative Emission system on your vehicle. The PCV system handles combustion byproducts while the EE system handles unburned hydrocarbons.

Boca's had this problem for 5 years. I'd suspect that he probably has driven with a partial tank many times by now. The system is designed to hold onto the vapors and not let them evaporate except when purging them into the intake manifold. Might be difficult to clear out a saturated canister short of replacing it...

 

No idea why I said pcv I meant evap system lol

 

Have ypur mechanic use pro link or whatever he uses to find out what psi the charcoal canister should be at then blow that much air through there and see if that helps for all you know there coukd be something that is making it get clogged.

 

I am in the habit of filling up even after 100 miles of driving or so. I read somewhere else ( although it sounds doubtful) that if I drive regularly at 1/2 tank or less, it might dry out the canister. It supposedly worked for another owner of a different car.. It's certainly worth a try right? I'm at half now and will drive to 1/4 and then fill back to 1/2. I'll try this for awhile and see how it goes. Thanks

 

Yup it was an audi =) and I had a feeling generally ls430 owners dont let there cars go below half tank, I hope it work out for you so you dont have to get the charcoal canister replaced let us know what happens.

 

I think I have to change how I fill my tank. I routinely fill mine up and top it off. With my commute, I usually go through a full tank in 3-4 days and average 450-500 miles per tank. I don't have any issues, and I don't smell any fuel, but I since I've been topping the tank for so long, I fear I may have damaged the evap canister already. I don't know if it makes a difference with how quickly I drain the tank, but perhaps the fuel level drops fast enough that I haven't done any harm yet.. Any thoughts? Gron? RKW? 05LS?

 

I have not experienced the P0440 DTC or smell of gasoline, and I too, always "top off" my tank. I don't believe that gasoline (in liquid form) can somehow travel up the lines and floods the canister. Attached is Toyota Training material on its EVAP system, which suggests (see page 5-6) that P0440 is caused by a leak on the fuel tank side. This leak is most likely the source of the gasoline smell.

 

Also, the term "top-off" can mean different measurement for different gas station - depending on how they calibrate the nozzle to shut off.

 

hey rkw, that training material is pretty amazingly good. Can DIYers get access to that stuff?

 

Fascinating reading with that Evap training material. I printed it off and it'll make great bathroom reading material...

 

Make sure you check the connection hoses on the driver side under the hood. I had the same code. I looked under my hood one day and seen a clap came off a hose and it was just hanging. Put it back and and it went away

 

Agreed this happen to me also and noticed the hose was disconnected. I also noticed that the hose has not pliable and after it happened the second time it broke into two pieces. I went to Lexus to replace it they gave me the wrong hose, even though I provided them the correct part number. I ended up having to bring in the old hose (two pieces) and they were so confused because the parts were mixed up. What's interested is they stated this was an error in the system and they would update/forward the information to be corrected.

https://www.clublexus.com/forums/sc4...and-p0446.html

 

I 3rd this when I installed my PPE headers I accidently unhooked the hose near the oil fill tube and it made a code for the evap system as well.