rx300 code P0440 what do I check?
Driver School Candidate
Joined: Nov 2017
Posts: 2
Likes: 0
From: Florida
Its been a few thousand and I've had the CEL come on twice.
Big difference from before when I could only go about a week before the CEL returned.
I suspect I have a wrong size clamp on one of the hoses (too big) and I'm not getting a complete seal.
I plan on looking at this soon but no hurry as it seems to be much better.
For what it costs and the effort, it's worth trying.
Best.
Big difference from before when I could only go about a week before the CEL returned.
I suspect I have a wrong size clamp on one of the hoses (too big) and I'm not getting a complete seal.
I plan on looking at this soon but no hurry as it seems to be much better.
For what it costs and the effort, it's worth trying.
Best.
Driver School Candidate
Joined: Aug 2019
Posts: 2
Likes: 0
From: FL
Thanks
Check the vacum hoses on air filter unit, terrible design function. So I just bought mt '02 RX300 last month with 101,000 miles on it in near perfect condition; one owner, grandma, all dealer maintained, all records = SCORE! However, after putting 4,000 mile on it in a month and a half I chose to get an oil change and tire rotation at Pep Boys in Lodi, CA for $24.99... Great deal and an oil change, any monkey can do that... Right? WRONG!!! After calling ahead to see if they could get it done in an hour, and getting assured that they could, I went down to get it done. After an hour and a half they came out to say that they were having trouble getting the filter out. Then after two hours they said all was done and I was ready to go. Two days later, my check engine light and VSC light came on, and needless to say I was upset after only making one payment so far. PB's offers free code reading so I took it in to get it read, codes came up P0040, P0046, and my VSC. PB said they then needed 150.00 to diagnose the issue, but having the codes I decided to take codes and do research myself and take it to the dealer if needed, as my confidence in PB was pretty low. After a google search I saw that someone else had this problem, and checked the air hoses under the car by the Charcoal Box, and no issue. Then I check the Air Filter box under the hood and sure enough, there was a hose on the back of the box that connected to another hose that runs under the car to the Charcoal Box... UNCONNECTED. Thats it, reconnect the damn hose and disconnect the negative terminal on the battery and ALL the codes are gone and gas mileage is back to +24mpg... Moral of the story... Do your homework before you pay.
I hope this helps save someone $$$ and stress. Fixed in 5 minutes work and 30 minute reset time.
I hope this helps save someone $$$ and stress. Fixed in 5 minutes work and 30 minute reset time.
Pit Crew
Joined: Oct 2013
Posts: 157
Likes: 0
From: California
Hi
I have a 2000 RX300 with 215k miles
A couple of years ago I would get a P0440 and I would clear it and it would come back a few months later, and this would repeat.
Lately is is happening about once a month or sometimes once every two weeks. I am only getting the P0440, none of the other P044x codes show up.
I replaced the gas cap but that hasn't helped.
I pulled the cover on top of the engine and inspected the vacuum hoses all look ok. and there are three vacuum solenoid valves mounted to the fuel rail . Two look like the same part and the third is different. The two that are the same part are often referred to vapor canister vent / purge valves. The third one is often called a vacuum control valve. I believe there is another located lower in front of the engine.
Does the vapor canister mounted by the gas tank have a valve?
I guess I will check the two bigger hoses that Brcobrem mentions above.
Is this the only thread that is strickley for the P0440?
Thanks in advance!
I have a 2000 RX300 with 215k miles
A couple of years ago I would get a P0440 and I would clear it and it would come back a few months later, and this would repeat.
Lately is is happening about once a month or sometimes once every two weeks. I am only getting the P0440, none of the other P044x codes show up.
I replaced the gas cap but that hasn't helped.
I pulled the cover on top of the engine and inspected the vacuum hoses all look ok. and there are three vacuum solenoid valves mounted to the fuel rail . Two look like the same part and the third is different. The two that are the same part are often referred to vapor canister vent / purge valves. The third one is often called a vacuum control valve. I believe there is another located lower in front of the engine.
Does the vapor canister mounted by the gas tank have a valve?
I guess I will check the two bigger hoses that Brcobrem mentions above.
Is this the only thread that is strickley for the P0440?
Thanks in advance!
CL Community Team
Joined: Apr 2001
Posts: 16,503
Likes: 1,369
From: Austin, TX
There are 3 different reasons listed in reverse order or probable cause.
a) Missing/broken control signal to a valve
b) Bad valve
c) Actual leak in the vacuum system.
I am predicting a slow leak which is getting worse over time.
Easy solution is a smoke detector but that again may be hard to detect as the smoke let out can be low. Smoke machine with soapy water can most likely detect the leak.
DIY method would be trace every connection and see if you notice a crack in the hose. If you are lucky, you may be able to smell gas vapors.
Using carb cleaner can be dangerous.
Salim
There are hoses around the charcoal canister which are hard to see readily as well as filler pipe. I also encountered a clean snap in hose, which appeared as if nothing is wrong, but when I wiggled the hose only one part moved.
Balance the aggravation again taking the vehicle to shop.
a) Missing/broken control signal to a valve
b) Bad valve
c) Actual leak in the vacuum system.
I am predicting a slow leak which is getting worse over time.
Easy solution is a smoke detector but that again may be hard to detect as the smoke let out can be low. Smoke machine with soapy water can most likely detect the leak.
DIY method would be trace every connection and see if you notice a crack in the hose. If you are lucky, you may be able to smell gas vapors.
Using carb cleaner can be dangerous.
Salim
There are hoses around the charcoal canister which are hard to see readily as well as filler pipe. I also encountered a clean snap in hose, which appeared as if nothing is wrong, but when I wiggled the hose only one part moved.
Balance the aggravation again taking the vehicle to shop.
Last edited by salimshah; May 9, 2021 at 10:05 AM.
Pit Crew
Joined: Oct 2013
Posts: 157
Likes: 0
From: California
My P0440 now seems to be persistent. It is there all the time, it no longer goes away and comes back.
I haven't had alot of time to troubleshoot it but will need to find the time.
I am going to start by looking at all the vacuum lines as well as testing the 3 VSVs. I believe there are 3 VSVs for the EVAP system, 1 at the canister, 1 at the air filter box and 1 on top of the front cylinder head. Please correct me if I am wrong.
I haven't had alot of time to troubleshoot it but will need to find the time.
I am going to start by looking at all the vacuum lines as well as testing the 3 VSVs. I believe there are 3 VSVs for the EVAP system, 1 at the canister, 1 at the air filter box and 1 on top of the front cylinder head. Please correct me if I am wrong.
1st Gear
Joined: Apr 2023
Posts: 1
Likes: 0
From: TX
I realize this is an old post. Curious if leak was ever found?
Toyota/Lexus systems can be challenging to diagnose. Confirming a leak with smoke machine flow meter reading is relatively simple. Connecting machine to tank via small vent hose to filler neck is most direct way. Note - Using vent or purge lines go through cannister which is not recommend. Confirming a tank leak is usually identified by smelling fuel vapors. The challenge comes trying to locate which item on top of tank failed. It appears the fill check valve is the most common however my local dealer states the #2 check valve is most sold.
Toyota/Lexus systems can be challenging to diagnose. Confirming a leak with smoke machine flow meter reading is relatively simple. Connecting machine to tank via small vent hose to filler neck is most direct way. Note - Using vent or purge lines go through cannister which is not recommend. Confirming a tank leak is usually identified by smelling fuel vapors. The challenge comes trying to locate which item on top of tank failed. It appears the fill check valve is the most common however my local dealer states the #2 check valve is most sold.
Driver
Joined: Jun 2022
Posts: 81
Likes: 22
From: CA
Checked my GS300 with a P0440, found the vacuum hose between air box to valve cover has a 2 inch crack. Taped it up with electrical tape. Will wait to see if that clears the code.
Thanks.
Thanks.
Do a search and you'll find that the system sometimes send P0440 Evap system codes for no reason, not necessarily a fault. Make sure the air filter housing and respective vaccum hoses are all properly connected and reset the code, I reset mine 1 year ago and never came back.
Highly unlikely that P0440 code is gas cap!
Highly unlikely that P0440 code is gas cap!
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