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I just experienced the p0440 and p0442 CEL's (evap Leak) on my 01' RX. My smoke test was unsuccessful in identifying the location of the evap leak. I wasn't surprised as the p0442 is considered a "small leak". I then sprayed numerous evap areas with soapy water while conducting a second smoke test and still couldn't identify any bubbles which would identify the leak. Therefore, I decided to replace several inexpensive items, fuel tank cap and 20 yr old vacuum hoses at the evap canister and hoses at the test port location adjacent to the throttle body as they all appeared dry-rotted. These items did not fix my leak so I assumed the leak was probably the infamous overfill valve located on the top side of the fuel tank. I'm told dropping the fuel tank on these models could take 20 hours labor without a lift. My 20yr old vehicle isn't worth much, so I decided to perform the overfill valve access-panel "hack", in lieu of dropping the fuel tank to gain access to this valve. By cutting my carpet and cutting an access hole in my floor with tin snips (do not cut with anything that could spark as fumes were significant at the valve) I saved a significant amount of time performing this hack. Upon cutting the access hole, I observed the typical hairline crack in the top of the overfill valve. I was able to replace the overfill valve and reinstall seat under two hours. I'll add a pic for anyone that wants to attempt this hack and needs help with the location of the new access hole.
After replacing the charcoal canister, i cleared the error codes, but after 200 miles 0440 came back...
I still get gas fume smell...specially on the passenger side. Could this be the Overfill check valve? Thoughts?
It could be many things, I had the same code and it was the OCV, but I never smelt any gas, the only way to be sure is a smoke test, thats what i did, took it to midus, put it on a lift, and when he tested the evap system, smoke poured out from the top of the gas tank, couldnt tell where exactly it was coming from, told me it would be $400 just to drop the tank and see, I noped the F out of there, did a bunch of research and found "fix it angel" on youtube and darn near every time he had one of those codes it was the check valve.
But I never smelt any gas and I drove for a long time with that code, so dunno, I'd bet $10 your check valve is bad, but theres about 20 different hoses up there and like 5 different "check valves" up there that could be bad too. Its not hard to drop the tank if your FWD but if your AWD its harder, look him up theres one he does on a highlander which is pretty similar, tank is much different but the idea is the exact same.
Just my two cents: there is also a plastic covered line that has a special "quick connect" that the check valve connects to, every time he did this repair he replaced that line and a few of the small rubber gas hoses that also connect to the gas tank, IMO it is far more worth it to do it this way, for just a few more bucks you increase your odds of never having to mess with it again, unless you make a noob mistake like I did and replace those rubber hoses with regular hoses instead of gas rated hoses and now have more leaks lol.
I am trying to solve my CEL P044x codes. I've been dealing with for a few years now. Checked solenoids, etc.
I'm pretty sure its the overfill check valve on the tank. I looked into dropping the tank but what a pain.
So I wanted to see exactly where would be the best place to cut on my RX for removing that check valve.
The car is 22 years old now, that's old enough to go under the knife for a nip and tuck.
I do smell fuel and she's putting out a bit of carbon monoxide (or unburned gas?)
It's registration time and she won't pass smog....
I am trying to solve my CEL P044x codes. I've been dealing with for a few years now. Checked solenoids, etc.
I'm pretty sure its the overfill check valve on the tank. I looked into dropping the tank but what a pain.
So I wanted to see exactly where would be the best place to cut on my RX for removing that check valve.
The car is 22 years old now, that's old enough to go under the knife for a nip and tuck.
I do smell fuel and she's putting out a bit of carbon monoxide (or unburned gas?)
It's registration time and she won't pass smog....
Which P044x code? Did you test the VSV's and canister?
Which P044x code? Did you test the VSV's and canister?
If I remember correctly (now my OBDII shows 0 Emission faults but I know they are there) it was P0440, P0441, P0442, and P0446. I made sure the VSVs in the engine bay were working correctly. I believe (It was some time ago when I first did this) I verified that the one on the canister was working also.
I can smell the fuel. My gas tank at one point used to make the sucking noise when I opened the cap but it no longer does. (I have replaced the cap but to no avail). I'm getting poor mileage.
I'm guessing that like many others my problem is the check fill valve.
2000 RX300 at about 110k miles. A couple of days ago it got CE light ON and an OBDII scan reading for code P0440:
Searched on this thread and started checking the air filter box and rubber tubes around it for potential leaks and found none. As the air filter box lid open, naturally I took the air filter out to check.
And I was surprised by what is in the box under the air filter! Some small smart creature made a living in it during the past winter!
The yellow debris appear to be fiberglass materials of insulation layers/panels, and I don't know where the little animals got them from!
As many of the experts on this forum suggested the P0440 code is for potential leaks in the emission system, would a "suffocating" air intake also present to the monitoring system as insufficient air due to leaks (hence causing P0440)?
I disconnected and reconnected the battery's negative terminal cable. After I driving some miles in the coming week, I will report back on the status of CE light and the P0440 code.
2000 RX300 at about 110k miles. A couple of days ago it got CE light ON and an OBDII scan reading for code P0440:
Searched on this thread and started checking the air filter box and rubber tubes around it for potential leaks and found none. As the air filter box lid open, naturally I took the air filter out to check.
And I was surprised by what is in the box under the air filter! Some small smart creature made a living in it during the past winter!
The yellow debris appear to be fiberglass materials of insulation layers/panels, and I don't know where the little animals got them from!
As many of the experts on this forum suggested the P0440 code is for potential leaks in the emission system, would a "suffocating" air intake also present to the monitoring system as insufficient air due to leaks (hence causing P0440)?
I disconnected and reconnected the battery's negative terminal cable. After I driving some miles in the coming week, I will report back on the status of CE light and the P0440 code.
Haha, oh boy you got critters!!!
The P0440 code won't come from a restricked air box IMO.
However, you will have vacuum lines coming from the back of the car to the components under the hood.
On the RX330 the vacuum lines coming from the back of the car are metal and then transition to rubber under the hood- these vacuum lines and the lines going to the components they hook up to are suspect first for that code.
Margate330: Thank you very much for sharing your insights - I will look more under the hood.
There is an exhaust leak near the Oxygen sensor (outside under the body positioned under the driver seat). The leak appears coming from where the hanger which is welded on the pipe - very difficult to patch up the leak without taking the exhaust section off as the hole is facing up within a metal structure piece on the pipe. Would such an exhaust leak causing code P0440?
About a year ago I took down the same pipe section that has the hole for the Oxygen sensor and used high-temp cement to seal off a hole (about the size of bean) there - MPG went up about 3 miles! This cement patch lasted thus far. My body has difficulty to bend down at the moment but will work on the leak as I recover.
Margate330: Thank you very much for sharing your insights - I will look more under the hood.
There is an exhaust leak near the Oxygen sensor (outside under the body positioned under the driver seat). The leak appears coming from where the hanger which is welded on the pipe - very difficult to patch up the leak without taking the exhaust section off as the hole is facing up within a metal structure piece on the pipe. Would such an exhaust leak causing code P0440?
About a year ago I took down the same pipe section that has the hole for the Oxygen sensor and used high-temp cement to seal off a hole (about the size of bean) there - MPG went up about 3 miles! This cement patch lasted thus far. My body has difficulty to bend down at the moment but will work on the leak as I recover.
Hi chenxingha, because the OP(orginal poster) titled the thread with the P0440 code this makes it easy for other members to search in the future so I will go ahead an elaborate on this code here.
-> Here is how the circuit works
-> Notice the dotted line in pic below, these are the components and vacuum lines suspect for this code P0440.
-> Someone correct me if I'm wrong but I think on the RX300 the charcoal canister is under the hood- so these vacuum lines and components would be easy to check for leaks and replace than the lines and components near the gas tank.
(Added below for fair use for commentary and discussion of P0440 code)
-> Here is a list of possible suspects, I would attack the easiest ones first and hope to get lucky.
PS- as far as the exhaust leak I would expect different codes but like to hear other member's ideas on this too.
10-09-17, 12:42 PM
2000 RX300 - Overfill Check Valve? p0440?
