EvlSmrk

My wife's 2003 RX300 is currently throwing the following codes:

P0441, P0442, and P0446

We're consistent with putting the gas cap back on, have reset the codes by unplugging the battery, and they still come up. They all point to the EVAP system, and either a faulty/dirty solenoid, cracked/broken/disconnected hose, or the gas cap. A local shop wants to run it through a smoke leakage check, and I'm inclined to let them unless anybody here can offer up some better suggestions.

Also, we're heading down to FL, with the Lexus, for my sister's graduation this week and am curious about what could happen if we wait to take care of it till we get back.

BillJoeBob

First check to see if the gas cap o-ring seal is cracked. If it's good and you know the cap is on tight next thing would be to check the evap cannister located under the rear of the vehicle on the side opposite the muffler. It has a large black plastic cover over it. You can remove this cover by removing 4 10mm nuts. Under the cover you will find a bunch of hoses and a couple of electrical solenoid valves.

It's probably best to take a picture of it with you phone, if capable, before removing any hoses or connectors in order to make sure you can get everything back on correctly. A couple of the hoses run to the gas tank to catch vapors in the big black cannister while the other hose runs to the intake on the engine. If you have any mechanical/electrical abilities you can try popping of some hoses/electrical connectors to do some basic checks. You might pop off a couple of hoses and try blowing through to possibly remove any blockage. Don't use compressed air of any significant pressure to do this. I usually pucker up and use my lungs. It tastes bad so be prepared to spit.

Topping off a gas tank has been known to cause a blockage. To blow through the lines going to the gas tank the gas cap need to be off. Also, I can't remember but some of the lines may have a one way valve so don't be surprised if you do feel a blockage. Most of this troubleshooting is really to just see if you can get the code to go away easily by doing rudimentary checks. If you feel electrically inclined you can check the resistance of the electrical solenoid valves. I don't recall the values you should get but if you get anything other than infinity (that indicates an open on the coil of the solenoid) on your electrical meter they are probably okay. I've gotten EVAP codes to go away by doing this on a couple of occasions. I once found a bad solenoid too. Best of luck.

BillJoeBob

A couple of images of the EVAP canister, hoses and electrical.
The red arrow point to a vacuum sensor, the blue the solenoid valve, and green the solenoid connector


Different perspective.
The blue arrow points to the solenoid valve again, and the black arrow to the EVAP cannister


Mine is a 99 model. I think the 03 models had an additional solenoid valve in the engine compartment near the intake air cleaner box

EvlSmrk

Turns out when my wife took the Lexus to Jiffy Lube, the hose that the small, short hose coming out of the air box came disconnected from the manifold it plugs into. I had checked the hoses on the air box, but didn't think to check further downstream than that. More expensive lesson than I wanted, but all in all was good news. Thank you for the advice and pics of the canister, I'll keep an eye on that if they show up again.

uw234

I am having the same issue. Check engine light went on 3 days ago, it's throwing the same codes.

Took it to my families mechanic, just got word back that it 'needs' a new canister - 575 for a new one!!!! He put in a request on the hotline for a used one, so we shall see what happens. In the meantime, I might try some of these pointers to see if I can get a quick fix...if maybe it's not the canister :/

BillJoeBob

I've never heard of a canister going bad. My guess is it's a bad component. If you've had any maintenance done recently check the hose integrity. Otherwise do an ohms check on the solenoids. It takes about 30 minutes at most to get the cover off and locate the right component. The toughest part is probing the end of the solenoid with the meter.