Question about P0441 code and under hood evap valve

Hey guys,
Long time lurker first time poster. I’ve got a 2013 TRD Sport V6 MT6 and recently had the P0441 code popping up again. Usually only happens in summer with heat and I assume fuel tank expansion. I replaced the gas cap (last summer) and occasionally grease the gas cap o-ring. I just pulled the under hood valve solenoid and bench tested using a dewalt 18v, clicked and opened as it should. Also I do usually top off at the pump to round up and read to stop doing that so hope it’s not too late. My question is regarding this item that appears to be some type of check valve? When I pulled it off it’s a straight shot through. Should there be some type of diaphragm inside there? Seems worthless unless it’s for some type of expansion or something. Haven’t seen much about this in all the threads so thought I’d post up to see if this might be my issue? Thanks in advance. Token shot of a recent trip thrown in there for good measure.

 

It’s a vacuum surge tank.
I’m not total sure of it’s purpose, but I’m guessing it “controls the rate at which vacuum is being created ”

This guys looks like yours.
https://www.clublexus.com/forums/rx...-found-a-parts-like-filter-but-it-is-not.html

I’d also look over all the EVAP lines and hoses for leaks.
The 0441 is for the Purge BSV Stu k Closed/Open.
A bad line or hose could cause this, as it wouldn’t allow the system to build vacuum or pressure.
When you tested the VSV, did you blow through the VSV in both Closed/Open?
Maybe the VSV is bad, even if it clicks?

 

That device is a vacuum accumulator and it is used to smooth the pulsing of the vacuum in the system. The same as the battery does in the vehicles electrical circuit. A buffer.

 

^^ This is correct, it insulates the fuel tank pressure sensor from vacuum vibrations while purging

P0441 is "incorrect purge flow detected" right?

That means that the pcm isnt seeing the pressure change it expects to see while commanding a purge.

Purge valve (at intake manifold) should be closed until commanded open. It has to hold vacuum at all times, even on the bench. Test it with a vacuum pump and a scan tool. It should open when commanded open

Vent valve (at the canister) should be open until commanded closed. Because they are open most of the time, they collect dirt and spider webs. Test it with smoke and a scan tool to turn it on/off and see if it seals.

It could still have a leak too even without a "evap small/large/gross leak detected" code.

 

EVAP codes suck. Good luck finding a solenoid that is actually failing when it is. The system is so finnicky and can fail under temperature related circumstances then start working again for an undetermined amount of time.

Replace your purge solenoid if you have no leaks and can confirm that you don't have any, your leak detection pump (AKA your vent valve) can fail subsequently one after the other, or at the same time. Unfortunately the leak detection pump on our trucks are expensive as a part alone and usually involves replacing the entire canister assembly itself which is incredibly not worth it.

Replace the purge valve, clear the code, and drive it as normal, if it returns unfortunately you will have to keep checking further down the pipeline. Like I said, EVAP is a horribly finnicky system.

 

This is a much more concise explanation

 

On a sidenote you, me, @TnShooter , and @Jimmyh are usually the main group of guys chiming into random threads attempting to help people diagnose their issues. I enjoy seeing the mini diagnostic crew we have here on the forum.

 

I was trying to sound responsible.. I'd probably diagnose it by throwing a purge valve it first

 

Hahahaha. Hey I don't blame you.

I usually like to try and eliminate leaks by smoking the system first, followed up by pressure testing the fuel cap, then performing an automated EVAP system self test if available via scan tool, followed up by an independent on-car test of the associated valve which I suspect may be causing the symptoms or is associated to the code, give it hell with my power probe and if I still can't prove it, replace the valve on a hunch and unfortunately just release the vehicle to the customer for driving, if they don't return then I'll know my educated guess was correct. If they do, well, I cross that bridge when I arrive to it. Lol.

In testing in this methodology though it helps me systematically eliminate variables starting from the simplest first eventually escalating my way up to the actual solenoids and hard parts to eliminate all variables prior to them potentially causing false codes.

 

I usually start by ripping the Scan tool out of the OBD port.
Followed by a an “explicit rant on my feelings of the EPA”

Nothing beats an 8+ hour trip back from Myrtle Beach, and the whole time a warning chime going off, telling me to “Tighten the Gas Cap”.

 

That made me laugh out loud.

 

Just don’t go to Myrtle Beach then...

 

Thanks guys for all the responses. Been driving this week and lights went off again randomly so I'm waiting to see if they return. I have not replaced the VSV at this point. Maybe my bench test with 18v popped something loose to start working again LOL.
Side bar question, in all the years I've owned the truck the gas cap only clicks one time when closing. You can kind of twist back CCW very slightly then click it again CW, you can do this over and over multiple times but still only one click. It does not click more than one time when turning CW ever! I thought I read others suggest 2-3 clicks and mine absolutely will not rotate any further. My wife's car will, as have other vehicles I own but never the truck. Is this the norm?

Thanks TnShooter,
I did blow through the VSV when open and closed, works as it should. I will add, I initially tried a 9v battery as I read in other posts and either the current was too weak or it needs a full 12+ volts to actuate. The 9v just barely clicked and did not fully open. That's why I went with the 18v drill battery. My scan tool reads "Evaporative Emission System Incorrect Purge Flow".

Correct on the code description. Not quite clear how I'd bench test it with a vacuum pump and a scan tool? I could run a vacuum pump on the VSV still on the vehicle and scan tool hooked up...

Thanks for the help so far guys. Anyone gone with the Fleabay VSV's for <$20?

 

Use a vaccum pump to see if it holds 18-21 inches of vacuum, use a scan tool to turn it on and off

But like Rob said, they can jump back and forth between working and not working, its just a little plastic valve. If you don't have any obvious leaks like a split hose or something you should just replace the purge valve, clear codes and see how it goes

Also my gas cap only clicks once when tightening too

 

I just did and it's an original Denso valve with Toyota scratched off.

 

My '12 would click 2-3x. Not even a month ago I replaced the cap and it's only 1x click and done. Not even a month later and the last two fill-ups I'm getting P0441 codes both times. I clear it and goes away. I'm wondering if I got a faulty cap from Toyota or if it's something else. Both the check engine and Trac lights come on giving me P0441. I'm at a loss+