In search of help with P0440 code

[OpenYota]

2001 SR5 4WD 170k
I’ve been throwing this code for a long time now and it’s sitting at pending again after just clearing the codes and I’m not sure what else to do about it and could use some suggestions.

Originally I was throwing P0440, P0441, and P0420 and have made these fixes to resolve with all new parts:

Replaced front/rear cat converters,
Both 02 sensors,
Vapor canister,
Overfill check valve & gasket,
Vent hose from check valve to Vapor canister,
Gas cap(it was from Amazon but was supposedly shipped from a Toyota dealer)

I had a smoke test ran on the car at a reputable mechanic and they said it was the canister so I had them replace it with an OEM part but I was still throwing a code so I did some research and changed the check valve on top of the gas tank along with a new gasket and hose.

I also checked the Ohms resistance on the two switch valves under the hood and both of them were reading correctly.
My truck isn’t all that rusty but I visually inspected the filler neck and it looked good; could it be the gasket to the fuel pump?
I could start replacing vacuum hoses and see if that helps.

I’m just looking for any other potential fixes and suggestions so any help would be appreciated as I need to try and pass emissions.

 

[Endlessblockades]

What condition is your exhaust system in from the cat to the tailpipe?

 

[Ph03n1x24]

I had a similar issue with a check engine light.
I replaced the gas cap with one bought from Amazon. (it was OE junk)
Bought an OEM gas cap from Toyota and it solved the problem.

 

[kevin8629]

02 sensor spacers may help your problem

 

[OpenYota]

What condition is your exhaust system in from the cat to the tailpipe?

It looks to be in relatively good condition, I don’t see any holes but I will listen for leaks next time I drive the car.
It was replaced by the PO.

 

[OpenYota]

I had a similar issue with a check engine light.
I replaced the gas cap with one bought from Amazon. (it was OE junk)
Bought an OEM gas cap from Toyota and it solved the problem.

I’m planning on doing this from my local dealer just for peace of mind soon; who knows this may be the issue.

 

[Endlessblockades]

Did you check out this post?

Fixed my P0440 Evap code too! 2002 SR5 4x4 - COMPLETE FUEL AND EVAP PARTS LISTS

 

[OpenYota]

Did you check out this post?

Fixed my P0440 Evap code too! 2002 SR5 4x4 - COMPLETE FUEL AND EVAP PARTS LISTS

Thanks for the recommendation; I have been on that thread a few times before.
I’m starting to wonder if the fuel filler neck is my issue as I don’t have a flap inside the neck itself and I also don’t get a slight whooshing sound when opening the gas cap so it seems like the system isn’t pressurised… could that be the culprit?

 

[19963.4lsr5]

Depending where you live the sealing surface on the gas tank rusts and causes the dreaded EVAP codes.

So if you can’t find anything wrong that would be the last most PITA step in your journey.

Sent from my iPhone using Tapatalk

 

[OpenYota]

Depending where you live the sealing surface on the gas tank rusts and causes the dreaded EVAP codes.

So if you can’t find anything wrong that would be the last most PITA step in your journey.

Sent from my iPhone using Tapatalk

I am also curious if this is my issue…
I dropped the gas tank to change the check valve and my fuel sending unit cover did look a little crusty underneath.
Did you replace the whole unit and if so, did it come with a new gasket or did you have to buy that separately?

 

[19963.4lsr5]

I am also curious if this is my issue…
I dropped the gas tank to change the check valve and my fuel sending unit cover did look a little crusty underneath.
Did you replace the whole unit and if so, did it come with a new gasket or did you have to buy that separately?

I cleaned up the sealing surfaces and bought new gaskets.


Sent from my iPhone using Tapatalk