Bax

I've been getting this code for a few weeks. I did top off the tank a time or two, I know better now. And every now and again I smell gas in the cabin just for a second and then it's gone.
Before I start trouble shooting here are few questions.

When you open the gas tank, is there any pressure?

I've had it so tight I almost could not get it lose.
Maybe a new gas cap.

If overflow form the gas went to the canister, shouldn't evaporate?
Hence the smell in the car.

I've got a manual to trouble shoot with.

What do you guys think?

Bax

salimshah

Check this thread:
https://www.clublexus.com/forums/rx-...lfunction.html

Your gas cap should have a replaceable gasket. See if is it cracked.

Inspection stations have a gizmo to check if the gascap is leaking.

When I fill gas, I tighten and count clicks. I leave it alone on the third click.

The proper procedure is to loosen the cap a bit and let pressure normalize. During very hot days I do hear a psst sound.

Salim

Z07

The code is set because the computer didn't receive the expected signal from the pressure sensing sending switch that monitors pressure in the tank. The normal mode of testing the integrity of the EVAP system is that the computer will command the vent valve closed and the purge valve open. After a few seconds it closes the purge valve too. This allows manifold pressure into the tank and EVAP system. The computer does this when the intake should be in vacuum. The system should hold most of that vacuum for the test cycle. If it fails there is freeze frame data stored. If it fails again on the next trip from cold to operating temp then the computer throws the code you saw and sets the CEL.

So why is your CEL on and why do you have P0446?



Every component in the EVAP system in that diagram is suspect until you rule them out or find the failure. Start with the easy one, the fuel cap. To check VSV's disconnect them and try to blow through them. Then power them with a jumper wire and try again. If powering them didn't change your ability to blow through them then they are failed. The purge valve and vent valve are opposites. The vent is normally (almost) open and closes when vacuum is applied to its diaphragm. The purge is normally closed and opens when vacuum is applied to its diaphragm. the canister is its own little world of tubes and one way valves. It is not cheap and I'm sure it is an automatic swap for dealers working EVAP problems. There was a TSB about them on RX's but I don't have the number. There is a test in the FSM for it but this one is probably very close or exactly the same Clicky

There are some cases (never heard of a Toyota) where canister failure will result in charcoal in the vacuum lines near it. So consider adding to your checks blowing through the lines.

Throwing parts at the problem will always fix it in the end. But if you take your time and divide the system into easy chunks you can figure out the exact problem and only spend money on what actually failed.

Bax

Hey Thanks.

Hey Salim, I am replacing the gas cap because my daughter has a hard time opening it even at a few clicks. Even though I will fuel the car most of the time. The pressure question probably does not not apply now that we have winter conditions in the US . No expansion due to heat.

Z07, I'm looking at "VSV for EVAP" as the problem. I am reading a few manuals to find the voltage at VSV before ruling out other stuff.....Excellent write up.

Does the test cycle happen at start up?


The RX is running fine. Mileage is about 18.5 stop and go. The LIE-O- meter shows 24.5. LOL .I just don't like the CEL on. It will be a few days before I can get back to it because of the holidays.

Bax

Bax

Update: I'm back at it. I have checked the components under the hood everything is in working order.

For the past month or two I can't fill the tank gas tank properly. The nozzle will click off as soon as I pull the handle. To get it to work i have to pull the nozzle out and squeeze about a third of the way to get it to work. And some times that doesn't work. I Have pulled it out almost to the top It still clicks off and I can see gas coming out of the nozzle. I don't think that is doing the charcoal canister any good. So I'm thinking the check valve or something with the filler hose, may be the root of my problems. The check valve is on the list to trouble shoot. And I will end up having to the replace the canister when I get the gas filling issue worked out.

I did a search on " not able to fill the gas tank "and there's not a lot of what I am experiencing.

Anyone else have trouble putting gas in the Tank before?

Bax