P2420 Code: Evaporative Emission (EVAP) System Switching Valve Control Circuit High with LRA Sub tank

[isthatalexus]

I have the 12 gal LRA. In the isntructions, mione indicated to fill with great caution and never Top Off the LRA. At first I didn’t read it, topped off, got the codes for a few days. Called installer, local Dallas, and he said drain it down. Run for a week, let fuel in canister evaporate refill but don’t overfill and then see if it still happens after clearing with OBD II. No issues since, same canister from factory never changed

A one-time saturation is probably survivable. I think the folks that have the really persistent problems have CCs which have suffered many, repeated saturations. My suspicion is also that when liquid fuel (as opposed to vapor) gets into the charcoal, the gasoline has a good chance of evaporating, but all kinds of additives stick around, gumming up the works for good.

 

[BIC JET]

A one-time saturation is probably survivable. I think the folks that have the really persistent problems have CCs which have suffered many, repeated saturations. My suspicion is also that when liquid fuel (as opposed to vapor) gets into the charcoal, the gasoline has a good chance of evaporating, but all kinds of additives stick around, gumming up the works for good.

Dang know-it-all! LOL!

 

[TeCKis300]

I'm not sure that the evap system ever test for charcoal canister efficacy. There's no real direct test for that.

Ultimately it's measuring to test that the system is sealed or leaking against a reference orifice. It's also checking for function of the VSVs, and circuit high/lo. But no direct test of the charcoal canisters function.

Flooding a charcoal canister would likely be temporary and recoverable.

The failure conditions are more likely that the VSVs failed, system has a leak, or canister internally is plugged due to contaminants or breaking down of the charcoal. All kind of require a replacement.

 

[isthatalexus]

Dang know-it-all! LOL!

Heh. If that were the case, I would not still be on here making wild, sometimes desperate, speculations.

 

[2021 LC200]

10% ethanol is probably not our friend for the evap system, valves or canister.

Which itself (ethanol) made from corn has been a disaster for food prices and makes most car consume almost 10% more. May as well sell us 10% air… One of the most useless moves made by our politicians who appear to have no clue about technical matters.

 

[2021 LC200]

Has anybody explored moving the factory canister higher up and is there space to do so?

 

[isthatalexus]

Has anybody explored moving the factory canister higher up and is there space to do so?

This is well-trodden ground for some folks. Here's a good example Factory sub tank - sourcing and fitment discussion - https://forum.ih8mud.com/threads/factory-sub-tank-sourcing-and-fitment-discussion.1239785/page-7#post-13664912

 

[MCtree]

I have been hesitating posting here for fear of jinxing myself, but after replacing the vent filter to no affect, I had the charcoal canister replaced about 3 weeks ago. Now with around 1500miles on the new canister I believe my issues are resolved. No more error codes.

Including installation the process cost me around $850. Money well spent if I don’t see those codes for even another couples of years (though hopefully longer).

And to circle back the the weight questions above. The new canister weighed 5lbs and 9oz, the old, failed one weighed 6lbs and 2oz. And the difference is a bit more actually in that the shop returned the old canister without the hose and wire that were attached to the new one when I weighed it.

 

[Boston Mangler]

Question for those that have had Evap and CC issues, and be honest....

After filling fuel and the pump kicks off, do you give the pump an extra squeeze for a bit more fuel? Be Honest...

Master ASE tech friend said this is root cause of most CC failures in many Toyota models, something about the excess after pump kicks off, goes right into the CC and eventually saturates it.

This happened on my 2014 Tundra with the 5.7 and i 100% admit i always have the pump a little more squeeze after it kicked off. CC was replaced under warranty at the time, and i have broken the habit of adding a little extra, and no issues since.

My unsolicited comment

 

[MCtree]

I never add more fuel after the click.
Never.
When I had the aux tank installed at Slee they warned me against this - and who am I to gainsay them?

That said, where I think I went wrong was leaving the pump from the aux tank to the main tank running for too long. For like half an hour after the main tank was full.
Normally I set a timer to avoid this but I got sloppy.

 

[TeCKis300]

Question for those that have had Evap and CC issues, and be honest....

After filling fuel and the pump kicks off, do you give the pump an extra squeeze for a bit more fuel? Be Honest...

Master ASE tech friend said this is root cause of most CC failures in many Toyota models, something about the excess after pump kicks off, goes right into the CC and eventually saturates it.

This happened on my 2014 Tundra with the 5.7 and i 100% admit i always have the pump a little more squeeze after it kicked off. CC was replaced under warranty at the time, and i have broken the habit of adding a little extra, and no issues since.

My unsolicited comment

I always go at least a couple more click on all my cars. In CA with the vapor recovery system, the pump stop is pretty sensitive. That works in conjunction with an internal fuel tank check valve. I've never experienced it truly trying to overfill - well only once but that was my other naughty cars fault.

IMO accidentally getting some fuel into the CC on occasion is not a root cause. The purge cycle will take care of excess fuel, regardless of vapor or liqued, when drawing vacuum and pulling it into the engine. There is nothing in the system that directly measures effectiveness of the charcoal.

What it does measure is orifice flow and that it can hold a vacuum. It's possibly over a long time, that the charcoal can break down, possibly by systemic flooding, that it then plugs flow and VSV function.

IMO, the more common root causes are VSV failure, or developing a leak. VSVs can fail with corrosion when water vapor gets drawn into the system as I've seen due to an LRA aux tank install.

 

[isthatalexus]

Question for those that have had Evap and CC issues, and be honest....

After filling fuel and the pump kicks off, do you give the pump an extra squeeze for a bit more fuel? Be Honest...

Master ASE tech friend said this is root cause of most CC failures in many Toyota models, something about the excess after pump kicks off, goes right into the CC and eventually saturates it.

This happened on my 2014 Tundra with the 5.7 and i 100% admit i always have the pump a little more squeeze after it kicked off. CC was replaced under warranty at the time, and i have broken the habit of adding a little extra, and no issues since.

My unsolicited comment

I run a 24gal LRA. I track MPG pretty carefully and primarily rely on calculated fuel level, because my gauge is unreliable; I probably borked something during fuel pump install. Unless gas goes over $4 (or news cycle goes into hysterics) I run the tanks sequentially. When filling up, I under-fill both tanks by ~2gal. That means I compromise about 9% of my full capacity (LRA 24 + OEM 24 = 48 - ~4 across both). When the fuelmaxxing 'spergers sets in, I drop a 5gal Jerry can on the back, and this makes my universe whole again. Note: I run a +/-$100 CC from a Camry or something, which I have reclassified as a consumable. And because you asked silently, with your mind: 12 city/17 highway, w/ about 70MPH top speed due to mods that make for brick-like wind tunnel dynamics. MPG drops to about 10.5 when I run ECT in the city.

 

[Artie]

This “add gas after the first click” convo is somewhat humorous given my most recent pump visit a couple hours ago. I never add more than the first shutoff, until today. The pump shut off early multiple times and I knew the main was no where near full. 14 gallons is all that went in and this after running 20 miles past the gas light and fuel range saying “Refuel”. It was for science… that’s what I told my wife, still got the side eye.

I’ve not had an issue with the CC but I do my best to avoid it and be as careful as I can. I can never get all 40 into my LRA, it’s always a couple shy of 40 so idk if I’m not getting it all out or it can’t get it all in. I change the breather filter once a year at least.

 

[gasman4u]

Question for those that have had Evap and CC issues, and be honest....

After filling fuel and the pump kicks off, do you give the pump an extra squeeze for a bit more fuel? Be Honest...

Master ASE tech friend said this is root cause of most CC failures in many Toyota models, something about the excess after pump kicks off, goes right into the CC and eventually saturates it.

This happened on my 2014 Tundra with the 5.7 and i 100% admit i always have the pump a little more squeeze after it kicked off. CC was replaced under warranty at the time, and i have broken the habit of adding a little extra, and no issues since.

My unsolicited comment

Assuming pump is functional and not shutting off early? No. I never fill fast the first click. This early shutoff is almost always remedied by some repositioning of the gas pump nozzle.

I just had my CC replaced. It was spendy, but I know it was done right and the tank was dropped correctly, etc. I hope this is a one off and not something that happens annually. That’d suck.

 

[ZetheGSD]

Question for those that have had Evap and CC issues, and be honest....

After filling fuel and the pump kicks off, do you give the pump an extra squeeze for a bit more fuel? Be Honest...

Master ASE tech friend said this is root cause of most CC failures in many Toyota models, something about the excess after pump kicks off, goes right into the CC and eventually saturates it.

This happened on my 2014 Tundra with the 5.7 and i 100% admit i always have the pump a little more squeeze after it kicked off. CC was replaced under warranty at the time, and i have broken the habit of adding a little extra, and no issues since.

My unsolicited comment

Such a true statement with old vs new Toyota models. If you’ve owned a bunch of Toyotas over the past 2-3 decades you may have noticed your early 2000’s and older Toyotas had the CC under the hood vs near the gas tank under the vehicle. I’m sure Toyota has multiple reasons (I know of a few) why they did this, but the unfortunate side effect is the canister becomes saturated much earlier and fails much sooner. I have experienced this multiple times with multiple vehicles.

A great example would be I’ve owned 8 different 3rd gen 4Runners and the 01-02 models have all had Canister issues requiring replacement during my ownership and the 2000 and prior models never needed it. What’s the difference between those year breaks? The Charcoal canister was relocated near the tank on the 01-02 models…

I know you can poke holes in that logic based on prior owners and mileage/usage, but even with tacomas of that vintage I rarely saw the under hood canister become saturated and need replacing. I can only report on my experiences and over 2 decades of owning multiple examples of the same vehicle with both designs. I usually top off my tanks to get as much range as possible. My 80 series has 340k on the clock and I am finally replacing the original canister in it. It is starting to do the vapor burp when I unscrew the fuel cap.

 

[ZetheGSD]

Such a true statement with old vs new Toyota models. If you’ve owned a bunch of Toyotas over the past 2-3 decades you may have noticed your early 2000’s and older Toyotas had the CC under the hood vs near the gas tank under the vehicle. I’m sure Toyota has multiple reasons (I know of a few) why they did this, but the unfortunate side effect is the canister becomes saturated much earlier and fails much sooner. I have experienced this multiple times with multiple vehicles.

A great example would be I’ve owned 8 different 3rd gen 4Runners and the 01-02 models have all had Canister issues requiring replacement during my ownership and the 2000 and prior models never needed it. What’s the difference between those year breaks? The Charcoal canister was relocated near the tank on the 01-02 models…

I know you can poke holes in that logic based on prior owners and mileage/usage, but even with tacomas of that vintage I rarely saw the under hood canister become saturated and need replacing. I can only report on my experiences and over 2 decades of owning multiple examples of the same vehicle with both designs. I usually top off my tanks to get as much range as possible. My 80 series has 340k on the clock and I am finally replacing the original canister in it. It is starting to do the vapor burp when I unscrew the fuel cap.

With that logic as well as adding an additional fuel tank in the same closed EVAP system, I would for sure not fill both tanks to the brim as you’d be saturating the canister immediately. Couple that with being Offroad and fuel is sloshing around non stop it’s a recipe for a clogged canister issue quickly. Add higher ambient temps to the mix and it gets substantially worse.

 

[gasman4u]

replacing the charcoal cannister with new OEM remedied my P2420 code for me immediately. Now I'm chasing another stubborn code that came on concurrently (P0441).

 

[BadReligion]

I am officially declaring the charcoal canister black magic. After having a continuous P0441, P2420, and P0455 (usually just one, sometimes all 3) for 3 months, and after numerous resets in hope that they would go away, I bought a new charcoal canister. Yearly smog was coming up and these are "permanent" codes that require a few start stop cycles without a code to clear. The thought of having to drop my subtank to get to the CC was more annoying than the cost of a new CC.

I set aside a whole Saturday and part Sunday for the project, and the Friday before, the light clears itself. I promptly smogged it so that was not a pressing factor. I thought the codes would certainly reoccur, but after a full month of driving, including high altitude heavy towing and using both regular and subtank, no lights.

Leading up to the codes, my breather filter got clogged in March with snow/ice and I couldn't fill either tank. My wife was driving at the time and forced a little fuel in both tanks trying to get enough in to make it home. I pulled the filter, cleaned it, cleared the codes, and all was fine. But the next time I filled up the aux tank, it took 12.6 gallons. I have never been able to get more than 11.5 in there, so that was really strange. It immediately threw all of the above codes and continued to do so for a solid 3 months, even after driving 2000+ miles, towing, offroading, etc. Kind of annoying when you are in the staging area of Hell's Revenge and you have to clear your evap codes so you can shift into 4LO. Good news is that once you are in 4Lo, you stay there even if the codes come back.

My best guess is that for some reason (maybe an issue with the auto shut off on the pump that allowed 12.6g), I completely flooded and saturated the CC. Then it took lots of driving (exhaust heat) and finally warm (95*+ temps) to finish evaporating all of the fuel in the charcoal, allowing it to function correctly again.

We'll see how long this lasts, but so far it seems resolved.

 

[Boston Mangler]

I am officially declaring the charcoal canister black magic. After having a continuous P0441, P2420, and P0455 (usually just one, sometimes all 3) for 3 months, and after numerous resets in hope that they would go away, I bought a new charcoal canister. Yearly smog was coming up and these are "permanent" codes that require a few start stop cycles without a code to clear. The thought of having to drop my subtank to get to the CC was more annoying than the cost of a new CC.

I set aside a whole Saturday and part Sunday for the project, and the Friday before, the light clears itself. I promptly smogged it so that was not a pressing factor. I thought the codes would certainly reoccur, but after a full month of driving, including high altitude heavy towing and using both regular and subtank, no lights.

Leading up to the codes, my breather filter got clogged in March with snow/ice and I couldn't fill either tank. My wife was driving at the time and forced a little fuel in both tanks trying to get enough in to make it home. I pulled the filter, cleaned it, cleared the codes, and all was fine. But the next time I filled up the aux tank, it took 12.6 gallons. I have never been able to get more than 11.5 in there, so that was really strange. It immediately threw all of the above codes and continued to do so for a solid 3 months, even after driving 2000+ miles, towing, offroading, etc. Kind of annoying when you are in the staging area of Hell's Revenge and you have to clear your evap codes so you can shift into 4LO. Good news is that once you are in 4Lo, you stay there even if the codes come back.

My best guess is that for some reason (maybe an issue with the auto shut off on the pump that allowed 12.6g), I completely flooded and saturated the CC. Then it took lots of driving (exhaust heat) and finally warm (95*+ temps) to finish evaporating all of the fuel in the charcoal, allowing it to function correctly again.

We'll see how long this lasts, but so far it seems resolved.

Yes.. this would confirm my (and several pro mechanic friends) suspicions of overfills killing the CC, over time, and throwing codes in the interim

 

[BadReligion]

I think it's absolute BS for Toyota to disable 4LO because of an evap code. I hope someone from Toyota is reading this. Probably not. And even if they are, it won't change anything. It's situations like this that make me appreciate a single computer 80 series.