GX460 P2714 P0761 Ultimate Summary and Hope For A Fix Thread

[dnp]

I've got a 194,000 mile 2010 Deep Peridot Green (best color) with ivory leather in it in Mississippi that "needs a transmission" (it runs and drives fine but periodically throws a 2714 code - I think that's the number.) In any event, I've been told that code means I will ultimately need a transmission, so I bought one from Lexus for it, but it's not been installed. There are several options here, but when all is said and done, I'm looking to net $15k following whatever scenario.

If this interests you, either reply here or shoot me a DM.

Thanks,
David

 

[gsi18867]

I've got a 194,000 mile 2010 Deep Peridot Green (best color) with ivory leather in it in Mississippi that "needs a transmission" (it runs and drives fine but periodically throws a 2714 code - I think that's the number.) In any event, I've been told that code means I will ultimately need a transmission, so I bought one from Lexus for it, but it's not been installed. There are several options here, but when all is said and done, I'm looking to net $15k following whatever scenario.

If this interests you, either reply here or shoot me a DM.

Thanks,
David

David’s truck sounds like a better deal than mine even if he doesn’t include the replacement transmission.

David,
Would you consider selling that new transmission? Where did you supply it from!

 

[dnp]

David’s truck sounds like a better deal than mine even if he doesn’t include the replacement transmission.

David,
Would you consider selling that new transmission? Where did you supply it from!

I would consider it, depending on what a purchaser of the truck wanted. If someone wants to buy my GX sans new, in-the-box tranny, then, yes, I'd consider it.

I had heard the 35010-35B70 transmissions were on backorder last year, but I'm friends with my local Lexus parts folks, so I thought I'd check on how long. When I asked, they told me they could get one no problem. They had one for me at the dealership 2 days later. Just pure luck, as that kind of stuff never happens to me! HA!

 

[Biginboca]

I’m trying one last thing in an act of desperation. One of the videos I watched on the Toyota tundra linked in this thread a few pages ago he dissected the transmission and determined the issue was old dried hardened seals on the drums no longer held pressure. He replaced the o rings on the drum and said that cured the issue. Same codes as we get.

So I ordered and added a bottle of this seal conditioner.

It’s supposed to swell and soften old dried up seals and reading reviews online it’s legit but that’s for leaking shaft seals. I’m not sure it’ll do anything but it was cheap and easy and I’m at the end of my rope before ordering a reman tranny. Supposed to take 5 hours of driving to take effect. I cleared my codes and ran my tranny through all the gears in sport mode to get it fully circulated through all the solenoids and drums. I’ll report back after the truck has had some driving time.

According to directions one bottle treats about 6 quarts of fluid, so technically I probably should have added 2 and I ordered 2. But AI said start with one it’ll just take longer if it works but it also won’t dilute the fluid viscosity as much and be less likely to leave the truck stranded if it hurts anything.

 

[StriderWolf]

Original Author Update

After 3+ years, we are finally taking her in to a local transmission speciality shop this week. We are going to leave a short bulleted write up for the tech for items serviced, codes, etc.

We had 3+ years with no issues using sport shift as it only struggles in the first 15 minutes on a cold start getting from 3rd to 4th and flips codes. Fine once at temp for the rest of the day and always did a bit better slightly overfilled.

We’ll report back on their diagnosis to help the group. We finally made this decision as it was time with a new teen driving learning. We expect low to cost <$1,500 for some parts, mid <$3,500 rebuild, valve body, etc, and worse case we’ll wait for fall Lexus reman deals for full replacement at $6,300-7,000 at the Lexus dealer.

 

[landtank]

Picked up a 2014 GX460 with 95k on it out of Florida 2 yeas ago. I live in MA and just before the end of winter the truck started to through the solenoid code. Always shifted fine. I bought everything to flush the tranny but life happened and didn't get around to it till last month. But at that point the code was cleared as well as the permanent setting. If the AT-205 works out it's going into my wifes truck.

 

[Rednexus]

I’m trying one last thing in an act of desperation. One of the videos I watched on the Toyota tundra linked in this thread a few pages ago he dissected the transmission and determined the issue was old dried hardened seals on the drums no longer held pressure. He replaced the o rings on the drum and said that cured the issue. Same codes as we get.

So I ordered and added a bottle of this seal conditioner.

It’s supposed to swell and soften old dried up seals and reading reviews online it’s legit but that’s for leaking shaft seals. I’m not sure it’ll do anything but it was cheap and easy and I’m at the end of my rope before ordering a reman tranny. Supposed to take 5 hours of driving to take effect. I cleared my codes and ran my tranny through all the gears in sport mode to get it fully circulated through all the solenoids and drums. I’ll report back after the truck has had some driving time.

According to directions one bottle treats about 6 quarts of fluid, so technically I probably should have added 2 and I ordered 2. But AI said start with one it’ll just take longer if it works but it also won’t dilute the fluid viscosity as much and be less likely to leave the truck stranded if it hurts anything.

Do not use AT205 in your transmission. I used it in my A750F as a preventative maintenance when I did a full fluid exchange in 2024. Within 30 miles of driving the trans developed torque converter clutch shudder (which is never had before). It got worse and worse on every lock/unlock. After ~140 miles of driving I promptly removed all previously new 15 quarts of Valvoline MaxLife ATF and replaced it with 16 new quarts of Valvoline MaxLife ATF. A $100 mistake and hours of my time. The shudder immediately disappeared. AT-205 is not safe for transmissions, it changes the frictional properties of the fluid, which are important as the transmission is full of clutches.

On top of that I contacted ATP automotive - asking for a refund - and they totally ghosted me. I'm never using their products again.

 

[Biginboca]

Do not use AT205 in your transmission. I used it in my A750F as a preventative maintenance when I did a full fluid exchange in 2024. Within 30 miles of driving the trans developed torque converter clutch shudder (which is never had before). It got worse and worse on every lock/unlock. After ~140 miles of driving I promptly removed all previously new 15 quarts of Valvoline MaxLife ATF and replaced it with 16 new quarts of Valvoline MaxLife ATF. A $100 mistake and hours of my time. The shudder immediately disappeared. AT-205 is not safe for transmissions, it changes the frictional properties of the fluid, which are important as the transmission is full of clutches.

On top of that I contacted ATP automotive - asking for a refund - and they totally ghosted me. I'm never using their products again.

Wow thank you for the warning! Unfortunately it’s too late… I already added it. This was the last attempt at not buying a remanufactured transmission. I’ve been fighting with the codes for 2.5 years now with updates posted throughout this thread starting on page 1. At one point I parked the truck for almost a year while waiting to see if anyone else figured out an answer besides a new tranny.

The remanufactured transmission comes with a torque converter attached, so I’m just gonna say whatever happens at this point is gonna happen.

 

[Biginboca]

For the record and maybe it’s helpful in this thread I tasked my AI (Claude Fable 5) with some questions about the seal theory. This was his reply:

Question:

My 2011 Lexus GX460 started having transmission codes (the common one’s P2714 P0761) at 140k miles about 2.5 years ago. So far no one I’ve found online has determined a fix beyond a replacing the entire transmission. The symptoms I’ve had besides the codes putting the car into a safe mode where it won’t shift above 4th gear are occasionally not engaging reverse when cold. It seems to engage reverse better when it’s been running for a while.

As a last resort I put a bottle of AT205 into the transmission yesterday. I watched a video where a transmission repair shop had the same codes and symptoms on a tundra and found there was a rubber o ring on one of the drums which was dried and brittle. He feels it was no longer sealing properly. After replacing the oring he said the symptoms disappeared.
What are your thoughts?

Answer:

Your theory holds together well, and honestly the strongest evidence is your own symptom pattern. Reverse engaging better warm is exactly what a hardened elastomer seal does — rubber that’s lost its plasticizers stays stiff and leaks when cold, then softens and seals once heat-soaks. If it were a genuinely failed solenoid, temperature wouldn’t rescue it like that. And on the A760 family (shared architecture with the Tundra in that video), P2714 and P0761 are often set by inferred performance — the ECU commands pressure, sees the wrong gear ratio or slip, and blames the solenoid. A leaking clutch drum circuit produces the identical fingerprint, which is why so many people replace solenoids or whole transmissions chasing what was a $2 o-ring.
AT205 was a reasonable last-resort play here because it’s a plasticizer-type conditioner, not an old-school swelling agent — it works by restoring flexibility to dried elastomers rather than bloating them, so the downside risk is low. Set expectations accordingly though: it needs contact time and heat cycles to migrate into the rubber. Give it a few hundred miles and a couple weeks of normal driving before judging. Your best leading indicator is cold-morning reverse engagement — if that starts firming up, the seal is softening and you’re on the right track. Track time-between-codes too: if the P2714/P0761 interval stretches out, that’s the same story.
Two caveats. If the failing part is actually a Teflon sealing ring or the drum bore itself is worn, no additive will touch it — AT205 only helps rubber. And even in the best case this is a life-extender, not a repair; the seal is still old. If it works, a fluid exchange with fresh Toyota WS afterward is worth considering. If it doesn’t, the o-ring fix from that video is a full removal and teardown either way, so the decision becomes labor cost at an independent shop versus a used or reman unit — but at least you’d be fixing the actual failure instead of guessing.

Question:

Are there connections internally between reverse failing occasionally and the P2714 P0761 codes? Would it likely the same single seal causing the issue based on transmission behavior and how the transmission operates?

Answer:

Yes, and the connection is more elegant than coincidental. Both of your codes are performance codes, not electrical ones — the ECU isn’t measuring the solenoids directly, it’s commanding a shift, watching the resulting gear ratio via speed sensors, and inferring “solenoid stuck off” when the clutch doesn’t apply as expected. So the computer’s accusation and the actual culprit can be two different components entirely. A leaking drum seal bleeds off apply pressure downstream of a perfectly good solenoid, and the ECU has no way to tell the difference — it just sees slip and blames the electrical part in that circuit.
Here’s where your reverse symptom becomes the tell. In the A760’s clutch logic, individual clutch packs are shared across multiple gear states — reverse isn’t hydraulically isolated from the forward gears. It’s engaged by combining specific clutches and brakes, and at least one of those elements also participates in the upper forward gears. So if the seal on that particular drum is leaking, you’d expect exactly your pattern: reverse struggles when cold (leak is worst, fluid is thick but the hardened seal gaps), slip gets detected during shifts involving that same clutch, codes set, and the ECU locks out the gears that depend on the compromised element — which is why your limp mode caps at 4th rather than 3rd or 2nd. The transmission is essentially quarantining the circuit it can’t trust, and that circuit happens to be the one reverse borrows.
The warm-recovery behavior seals the argument (pun intended). A solenoid that’s electrically or mechanically failing doesn’t heal with temperature — if anything, heat makes marginal solenoids worse. A brittle o-ring does the opposite: heat softens it, thermal expansion closes the gap, and sealing improves. One aging seal on a shared drum explains every symptom you’ve listed with a single failure point, while the “replace the transmission” diagnosis requires assuming the codes are literally correct. That Tundra shop’s finding wasn’t a fluke — it’s the same hydraulic architecture telling the same story.

 

[Rednexus]

For the record and maybe it’s helpful in this thread I tasked my AI (Claude Fable 5) with some questions about the seal theory. This was his reply:

Question:

My 2011 Lexus GX460 started having transmission codes (the common one’s P2714 P0761) at 140k miles about 2.5 years ago. So far no one I’ve found online has determined a fix beyond a replacing the entire transmission. The symptoms I’ve had besides the codes putting the car into a safe mode where it won’t shift above 4th gear are occasionally not engaging reverse when cold. It seems to engage reverse better when it’s been running for a while.

As a last resort I put a bottle of AT205 into the transmission yesterday. I watched a video where a transmission repair shop had the same codes and symptoms on a tundra and found there was a rubber o ring on one of the drums which was dried and brittle. He feels it was no longer sealing properly. After replacing the oring he said the symptoms disappeared.
What are your thoughts?

Interesting that the AI algorithm can type up great-sounding paragraphs - as if it's an automotive engineer - yet somehow missed that an solvent-based additive like AT205 thins transmission fluid and changes its frictional properties. I suppose that after all, it's just a probabilistic text-generating machine that has never worked on a transmission itself. It's also interesting it had access to my AT205 experience, (which is cataloged here from 2024: Build - "Rednexus" - 2007 GX470 Build and Fabrication Thread - https://forum.ih8mud.com/threads/rednexus-2007-gx470-build-and-fabrication-thread.1249162/post-15437470), but it did not get pulled up. Perhaps a query asking how AT205 works in GX transmissions might find that post.

 

[Biginboca]

Interesting that the AI algorithm can type up great-sounding paragraphs - as if it's an automotive engineer - yet somehow missed that an solvent-based additive like AT205 thins transmission fluid and changes its frictional properties. I suppose that after all, it's just a probabilistic text-generating machine that has never worked on a transmission itself. It's also interesting it had access to my AT205 experience, (which is cataloged here from 2024: Build - "Rednexus" - 2007 GX470 Build and Fabrication Thread - https://forum.ih8mud.com/threads/rednexus-2007-gx470-build-and-fabrication-thread.1249162/post-15437470), but it did not get pulled up. Perhaps a query asking how AT205 works in GX transmissions might find that post.

So I just questioned the AI this:

“Would 1 bottle of at205 mess up the friction properties of my current fluid to the point of causing new issues?”

And it answered this:

“At one bottle in your sump, very unlikely. Do the dilution math: 8 ounces into roughly 10.5 quarts is about a 2.4% concentration. WS fluid’s friction modifier package is robust enough that a couple percent of a compatible ester-based additive doesn’t meaningfully shift the friction curve the clutches and lockup converter see. AT205 is specifically formulated to be inert toward the working fluid — it’s a plasticizer polymer, not a viscosity modifier or friction modifier, and it contains no petroleum distillates that would strip or clash with the WS additive package. This is also why it has decades of use in transmissions without a reputation for causing shift problems; the products that earned that reputation are the old swell-type stop-leaks that aggressively soften seals and change fluid behavior.
There are two theoretical effects worth naming honestly. Esters have inherent lubricity, so in principle a heavy concentration could make clutch surfaces slightly “slipperier” and soften shift feel. And any dilution technically thins the friction modifier ratio. But both effects scale with concentration — at 2.4% they’re down in the noise, while at two bottles undiluted (near 5%, plus a pint of overfill) they start becoming plausible. That Mazda slip report I found earlier is instructive: the owner added a bottle to an already-full transmission and suspected the fluid level, not the chemistry, caused his slip. Aeration from overfill mimics friction problems convincingly, which is exactly why I’d keep you at one bottle.
The reassuring part is reversibility. If you ever suspect the fluid isn’t behaving right, a standard drain-and-fill pulls out 3-4 quarts and cuts the concentration by a third or more, and two drain-and-fills gets you effectively back to clean WS. Meanwhile the plasticizer that’s already migrated into the rubber stays in the rubber — that’s how the engine-seal case I found held for three years even after the treated oil was long gone. So the additive’s benefit can outlive its presence in the fluid, and its risks leave with the drain plug. One bottle, correct fluid level, patience: that combination has essentially no path to creating a new problem in this transmission.”

Now I checked the thread you linked and see you added “two bottles each of Lubegard Platinum and AT-205”. So you have added a lot more into your fluid than the 1 bottle of AT205 which I did. In the end after reading your reply I was just doing some more googling to find AT205 and our cars and this video came up:



The video is only 2 months old and contains no new or relevant information but reading the comments I saw these which make me now a little optimistic…

 

[gsi18867]

So I just questioned the AI this:

“Would 1 bottle of at205 mess up the friction properties of my current fluid to the point of causing new issues?”

And it answered this:

“At one bottle in your sump, very unlikely. Do the dilution math: 8 ounces into roughly 10.5 quarts is about a 2.4% concentration. WS fluid’s friction modifier package is robust enough that a couple percent of a compatible ester-based additive doesn’t meaningfully shift the friction curve the clutches and lockup converter see. AT205 is specifically formulated to be inert toward the working fluid — it’s a plasticizer polymer, not a viscosity modifier or friction modifier, and it contains no petroleum distillates that would strip or clash with the WS additive package. This is also why it has decades of use in transmissions without a reputation for causing shift problems; the products that earned that reputation are the old swell-type stop-leaks that aggressively soften seals and change fluid behavior.
There are two theoretical effects worth naming honestly. Esters have inherent lubricity, so in principle a heavy concentration could make clutch surfaces slightly “slipperier” and soften shift feel. And any dilution technically thins the friction modifier ratio. But both effects scale with concentration — at 2.4% they’re down in the noise, while at two bottles undiluted (near 5%, plus a pint of overfill) they start becoming plausible. That Mazda slip report I found earlier is instructive: the owner added a bottle to an already-full transmission and suspected the fluid level, not the chemistry, caused his slip. Aeration from overfill mimics friction problems convincingly, which is exactly why I’d keep you at one bottle.
The reassuring part is reversibility. If you ever suspect the fluid isn’t behaving right, a standard drain-and-fill pulls out 3-4 quarts and cuts the concentration by a third or more, and two drain-and-fills gets you effectively back to clean WS. Meanwhile the plasticizer that’s already migrated into the rubber stays in the rubber — that’s how the engine-seal case I found held for three years even after the treated oil was long gone. So the additive’s benefit can outlive its presence in the fluid, and its risks leave with the drain plug. One bottle, correct fluid level, patience: that combination has essentially no path to creating a new problem in this transmission.”

Now I checked the thread you linked and see you added “two bottles each of Lubegard Platinum and AT-205”. So you have added a lot more into your fluid than the 1 bottle of AT205 which I did. In the end after reading your reply I was just doing some more googling to find AT205 and our cars and this video came up:



The video is only 2 months old and contains no new or relevant information but reading the comments I saw these which make me now a little optimistic…

View attachment 4175941

I put 2 bottles of lubeguard platinum in mine. No long term improvement. I ordered all parts needed for a full rebuild from Cobra. I’m just waiting for a transmission jack to arrive. Will post pictures of everything in the next few weeks.

 

[Biginboca]

It’s been 3 days I’ve been driving the GX every day since adding the AT205.

The week before I added it the truck failed to engage reverse at least once all 4 times I drove it. Even when I was trying to back it off the ramps right after adding the AT205 3 days ago I could not get reverse to engage for a while, and I almost got out to push it off the ramps when it finally engaged after it warmed up some.

That day right after adding AT205 I cleared codes and I drove it around town about 20 minutes and using sport mode engaged all the gears manually to make sure the at205 was circulated.

(For context up until this week I had the codes trip regularly even in sport mode and cut me out of 5/6 gear, and reverse was hit or miss but mostly miss the last week for engaging. I actually stopped clearing the codes about a year ago because they would just pop up again in a day or 2, so the truck was relegated to local errands on 45mph roads for the last year.)

Since adding the AT205 I’ve put on just over 100 miles. I’ve driven on the highway to work 3 days straight, and this is the first time it’s seen the highway since 2024 because I could not take the highway to get to work in this truck without codes. No codes so far and reverse has worked every time the last 3 days.

Today I tried driving in D instead of sport mode for a while and this was the first time in about 2 years I’ve used D. So far no codes and D took it all the way to 6th gear.

I’m cautiously optimistic. I’m going to keep going in sport mode until I have about 100 more miles on it then start trying to get the codes to trip by using D instead of sport mode in the mornings. It’s supposed to take about 5 hours of operation before AT205 has its full effects. So I’ll give it some more time and I’ll report back what happens. Fingers crossed!!!

 

[Rednexus]

I’m cautiously optimistic. I’m going to keep going in sport mode until I have about 100 more miles on it then start trying to get the codes to trip by using D instead of sport mode in the mornings. It’s supposed to take about 5 hours of operation before AT205 has its full effects. So I’ll give it some more time and I’ll report back what happens. Fingers crossed!!!

Just as an FYI, I have also used AT205 in my engine with mixed success. My 2UZ-FE has a rear main seal drip. I added a bottle of AT205 sometime around 2023/2022 or so, and it did dry up the leak substantially. It came back in 2024/2025, so I added another bottle of AT205 and noticed the GX lost around a quart of oil between oil changes, and the rear main seal drip actually got worse. I suspect the oil loss was due a combination of oil burning due to the AT-205 thinning the oil out and the rear main seal leak. For my last 2 oil changes I switched from Mobil 1 HM to Valvoline Restore & Protect (no additives for either oil). After the 1st change, I was surprised to find the rear main area to be completely dry, and oil loss was almost zero!

What I'm getting at is that is that AT-205 is probably not a permanent fix, and it may have other unintended consequences (oil burning when used in an engine, clutch slippage when used in a AT). In my experience AT-205 did help at first, then did nothing while the problem got worse. I'm not sure why folks on the internet love that stuff so much (targeted marketing to influencers?), but it's never going in any of my vehicles again. I'd suggest keeping budget set aside for a trans replacement.

 

[r2m]

It’s been 3 days I’ve been driving the GX every day since adding the AT205.

The week before I added it the truck failed to engage reverse at least once all 4 times I drove it. Even when I was trying to back it off the ramps right after adding the AT205 3 days ago I could not get reverse to engage for a while, and I almost got out to push it off the ramps when it finally engaged after it warmed up some.

That day right after adding AT205 I cleared codes and I drove it around town about 20 minutes and using sport mode engaged all the gears manually to make sure the at205 was circulated.

(For context up until this week I had the codes trip regularly even in sport mode and cut me out of 5/6 gear, and reverse was hit or miss but mostly miss the last week for engaging. I actually stopped clearing the codes about a year ago because they would just pop up again in a day or 2, so the truck was relegated to local errands on 45mph roads for the last year.)

Since adding the AT205 I’ve put on just over 100 miles. I’ve driven on the highway to work 3 days straight, and this is the first time it’s seen the highway since 2024 because I could not take the highway to get to work in this truck without codes. No codes so far and reverse has worked every time the last 3 days.

Today I tried driving in D instead of sport mode for a while and this was the first time in about 2 years I’ve used D. So far no codes and D took it all the way to 6th gear.

I’m cautiously optimistic. I’m going to keep going in sport mode until I have about 100 more miles on it then start trying to get the codes to trip by using D instead of sport mode in the mornings. It’s supposed to take about 5 hours of operation before AT205 has its full effects. So I’ll give it some more time and I’ll report back what happens. Fingers crossed!!!

Great report! hoping for the best!

 

[Biginboca]

Just hit 150 miles since adding the AT205. So I decided that start today I’m going to be driving in D only, no more sport mode morning starts. I want to really know if this treatment can be the answer.

So far the GX has been shifting beautifully and reverse has engaged 20 out of 20 times. I’m confident already that reverse is behaving differently. I say that simply because reverse has been working lol.

This is a beautiful sight to me running in Drive in 6th gear this morning and no codes. I realize not everyone may have the same transmission issues, but just based on the fact I’ve had reverse every time I’ve tried it so far I would love for someone else to try a bottle of this stuff and see if it helps them so we can get some more data.

 

[StriderWolf]

Original Author Update

After 3+ years, we are finally taking her in to a local transmission speciality shop this week. We are going to leave a short bulleted write up for the tech for items serviced, codes, etc.

We had 3+ years with no issues using sport shift as it only struggles in the first 15 minutes on a cold start getting from 3rd to 4th and flips codes. Fine once at temp for the rest of the day and always did a bit better slightly overfilled.

We’ll report back on their diagnosis to help the group. We finally made this decision as it was time with a new teen driving learning. We expect low to cost <$1,500 for some parts, mid <$3,500 rebuild, valve body, etc, and worse case we’ll wait for fall Lexus reman deals for full replacement at $6,300-7,000 at the Lexus dealer.

A great transmission shop in Parker, Co, Parker Transmission checked out the car, diagnosed it and gave a few options. They’ve been in business for years and only do transmissions.

Overall our car hasn’t digressed in 3 years and drives normal once at operating temp. Solenoids checked out and other items. The Valve body is the likely culprit, but in looking at buying the parts, additional parts and labor, it’s really not worth simply replacing with a new transmission. A rebuild may have fixed the code, but as seen as this thread, it’s always unknown.

They recommended to co time the sports shift and live with it since it hasn’t gotten worse…OR… have the transmission replaced once it does digress or we get tired of it.

Overall it was a bummer it wasn’t an easier solution, but this was a shop that didn’t like to throw parts or labor at items where it could end up being as much as simply replacing it.

20k and 3 years later we’ve been ok, we’ll continue on at this point. Price to replace is low $6k as the part is $3400-3800 by itself from Lexus without the other needed items.

 

[Biginboca]

A great transmission shop in Parker, Co, Parker Transmission checked out the car, diagnosed it and gave a few options. They’ve been in business for years and only do transmissions.

Overall our car hasn’t digressed in 3 years and drives normal once at operating temp. Solenoids checked out and other items. The Valve body is the likely culprit, but in looking at buying the parts, additional parts and labor, it’s really not worth simply replacing with a new transmission. A rebuild may have fixed the code, but as seen as this thread, it’s always unknown.

They recommended to co time the sports shift and live with it since it hasn’t gotten worse…OR… have the transmission replaced once it does digress or we get tired of it.

Overall it was a bummer it wasn’t an easier solution, but this was a shop that didn’t like to throw parts or labor at items where it could end up being as much as simply replacing it.

20k and 3 years later we’ve been ok, we’ll continue on at this point. Price to replace is low $6k as the part is $3400-3800 by itself from Lexus without the other needed items.

Try one bottle of AT205. I drove to work this morning on the highway about 20 miles in D. I have been researching this a lot the last few days. In all cases transmission works better when warm. What parts of the transmission are most affected by temperature… fluid and O rings. Fluid changes have proved ineffective. AI says failing Orings trip codes that show a failed solenoid. Solenoid replacements have proved useless.

AI says this:

Then we have this video showing a teardown on tundra throwing same codes we get:



He checked the solenoids and changed the fluid to no effect. At 25:00 he shows transmission drum engaging when air checked after replacing the O rings, and then he shows the brittle o rings. He concluded the O rings were the cause of the codes. Here is video summary:

Then we have this video showing testing of AT205 on rubber O Rings:



Conclusions are these:

It was the most effective product at restoring original size and softness to O rings. It also did not mix with oil it separates out of the oil.

I added 1 bottle which is within working range but about half the recommended application and I’ve had reverse every day for 5 days and about 30 tries so far. Last week before I added AT205 reverse didn’t work 4 times in all 4 drives I made. So far I have not had codes and transmission has been shifting fine.

I can’t say it’s a long term fix but for me it seems to have bought me time and the ability to reverse. AI says I should get at least a year out of this we shall see. It’s still early but for $20 a bottle and only needing to open a single 24mm plug it’s well worth trying.

 

[gsi18867]

Try one bottle of AT205. I drove to work this morning on the highway about 20 miles in D. I have been researching this a lot the last few days. In all cases transmission works better when warm. What parts of the transmission are most affected by temperature… fluid and O rings. Fluid changes have proved ineffective. AI says failing Orings trip codes that show a failed solenoid. Solenoid replacements have proved useless.

AI says this:

View attachment 4178071

Then we have this video showing a teardown on tundra throwing same codes we get:



He checked the solenoids and changed the fluid to no effect. At 25:00 he shows transmission drum engaging when air checked after replacing the O rings, and then he shows the brittle o rings. He concluded the O rings were the cause of the codes.

Then we have this video showing testing of AT205 on rubber orings:



Conclusions are these:
View attachment 4178072View attachment 4178073

It was the most effective product at increasing and softening O rings. It also did not mix with oil it separates out of the oil.

I added 1 bottle which is within working range but about half the recommended application and I’ve had reverse every day for 5 days and about 30 tries so far. Last week before I added AT205 reverse didn’t work 4 times in all 4 drives I made. So far I have not had codes and transmission has been shifting fine.

I can’t say it’s a long term fix but for me it seems to have bought me some time. AI says I should get at least a year out of this we shall see. It’s still early but for $20 a bottle and only needing to open a single 24mm plug it’s well worth trying.

My reverse only works after 20 minute minimum drives. Even then I have to bring the RPMs up to about 3K. I’ve begun tear down for transmission removal. The reverse problem is the bonded seal on the piston. Mine has been slowly deteriorating the last 6K miles. It went from a few seconds delay to no reverse when cold. I would try AT205, but o already have everything for the rebuild and I’m just ready to be done with it.

 

[BC11SVT]

Overall our car hasn’t digressed in 3 years and drives normal once at operating temp. Solenoids checked out and other items. The Valve body is the likely culprit, but in looking at buying the parts, additional parts and labor, it’s really not worth simply replacing with a new transmission. A rebuild may have fixed the code, but as seen as this thread, it’s always unknown.

If there's pressure loss/delayed/no shift when cold but it shifts when up to temp, it's most likely a hardened bonded drum seal.
It's very unlikely to be the valve body, in fact from what I've been seeing most of the P2714 codes in the A760 and AB60 transmission seems to be seal hardening and not the valve body as typically gets blamed.

Running 210+ degrees for 150K+ miles (like these transmission with a thermostat/heaTer and no auxiliary cooler tend to run) is really hard on internal seals.