I just replaced my hoses today. I'll confirm your comments that there is not much difference between the old and new hoses. The old hose was black and the new hose is dark gray, maybe they are made from a different material but it is similar.

Installation is relatively simple. You do have to move the injector driver boxes to get access to the engine side where the hoses connect. Two 10mm bolts and one 10mm nut hold each one on. Remove those and move the boxes slighlty out of the way. Be careful not to manhandle the boxes, the wires that are connected are on the small side.

 

Lately, I've been intermittently getting some hesitation when using light throttle going up hills. To put it another way, when I am trying to maintain speed or gradually accelerate up an incline, I can feel a slight lapse in the acceleration. It's been about 10k miles since my last throttle body incident, and this makes me wonder if it's going to happen again. It could also be something totally different - transmission, maybe?

 

I've had a similar experience on and off, starting around 10k miles. My 2023 is just over 20k, and occasionally it will happen randomly when in ECO or Normal mode. Mainly when going uphill and trying to keep a steady speed/rpm. These are not steep inclines either. Just some random hills or a slight grade. It occurs with and without cruise control on, between 25-65mph roughly. It comes on almost like a pulsing/surging feel.

A couple of things to note. I'm at a higher altitude 7200' above sea level, and temperatures vary from 60-80 degrees most days when it's happened. The engine and transmission are completely warmed up, and no spirited (WOT) driving before the occurrences. The gas tank was never below a half tank when I experienced the issue.

The dealership has attempted to duplicate the issue, but could not. They believed at first that the issue was the transmission searching for gears. I wondered the same thing. Before bringing it to the dealership, each time I would approach a hill/incline expecting it to occur, I would set the display to the gear selection screen. The gear selection didn't change, and I can say on average it's in 5th gear most times. I've never had it occur in Sport or Sport+ either. Most likely due to the dynamic setting changes in the throttle and transmission response

The only issue the dealership could determine was that my transmission fluid was about 1qt low. They topped it off, and there has been no improvement. They checked over the mapping/programming for any transmission issues but came up with nothing.

I questioned the throttle body issue and the fuel pump. They said that unless either of them completely fails, they won't replace either.

Pretty frustrating, and I hope not to be stranded anywhere due to a faulty throttle body or fuel pump issue.

 

Some of you with slightly higher mileage, it wouldn’t hurt to clean the throttle body. I bet if you pulled it off, it would be pretty dirty

 

Hmm - Just spitballing here But, I wonder what the incidence is of this happening on the 2UR-GSE with and without a catch can (oil/air separator - AOS)

Lou

 

Here's another datapoint since this thread was super helpful for me a few days ago.

My 2024 IS500 with 12,800 miles threw a CEL and multiple warning lights (no traction, no collision detection, etc.) while idling in a parking lot. Thankfully, the car didn't lose power and I was able to drive it home. I scanned it and found code P2111.

I took it to the dealer the next day, but when they turned the car off so I could speak with the advisor, the CEL and warning disappeared. I showed my service advisor the LSB which she initially ignored (she already thought I was crazy because there was no CEL when she started the car again). Fortunately, the CEL came back a few minutes later while the car was idling in the service lane.

They replaced the throttle body and hoses the next day and so far the car is running great. Once again thanks for this thread!

 

Hi everyone,

New member here & a proud owner of 2025 model in USB; I just experienced this throttle body issue today while pulling into a grocery store parking lot (CEL & a bunch of other lights came on). Car only has around 5200 miles since purchased last May.

Fortunately there was a Lexus dealer literally 10 min away, and I was able limp in at around 5:30 PM (with my family along for the ride) with the dealer closing at 6 PM. They diagnosed the TB stuck issue & gave me a loaner.

But what's alarming is that going by an earlier post in this thread:

"According to that TSB which was updated July 2025, it applies to 2022-2025 IS500s (as well as the other usual models) produced BEFORE VIN series JTHAP1D2#S5007419"

My car shouldn't be affected, since my VIN ends in 7551.

So is Lexus lying to us here? Not very happy for this to happen on a pretty much brand new made in JAPAN car.

 

That is not good news! Hopefully this is a fluke but keep us posted on what the dealer says.

 

OK just a follow-up post now that I had time since last night to think & re-read through this thread and do more research on throttle body; just some further thoughts/rants:


1. I downloaded & looked through the L-SB-0032-25 PDF that was posted earlier in this thread. It confirms that Lexus themselves posted that cars w/ VIN before JTHAP1D2#S5007419 is not part of the TSB and thus should have the new TB parts. Well that turned out to be false (again mine was 7551), so I'm going to bring this to the dealership's attention when I go to pick up my car & maybe contact Lexus USA and call them out on this. Absolutely alarming to see this wrong info; does this mean that the new parts don't work, or Lexus spewing BS here? Also the part # for the replacement TB assembly w/ motor 22030-38050 did NOT change; is this actually a NEW part? How can we be sure that the TB issue won't come back after replacement?

2. When I spoke to the service manager yesterday at the dealership, she mentioned that the TB was a defective part that goes back to 2014. Now this lines up with what has been posted in this thread & in the TSB, that it affects all the cars w/ the 2UR-GSE engine. But from my research, it doesn't seem like the other F cars are experiencing this issue?

3. From my research normally TB shouldn't experience issues/failures until high mileage age due to dirt/buildup. Can driving behavior play a part here? FYI I mostly drive my 500 in Eco & Normal mode, and I'm pretty gentle on the gas pedal; I haven't bounced off the rev limiter or do any extreme driving since I treat my car like a panda (knowing Lexus now stopped making NA V8 cars). So I'd think it's not my driving behavior that's causing the TB issue?

4. I'm going to catch some heat for saying this, but between the known valley plate leak and now this TB issue, the 2UR-GSE might not been as reliable/bulletproof as people make it out to be (overhyped?). I intended to keep my 500 as a forever car, but now this has me questioning that intention. I actually considered the M340i before choosing the IS, and now I'm starting to rethink that decision. I'd think that BMW turbos & cheap plastic Chinese engine parts would last at least a year before throwing error codes!

 

People have commented that the TB itself is the same part number and therefore, the same part as before. Only the 2 hoses were of a different part number and that was supposed to correct the issue. We will have to wait and see if more 500 owners develop this issue...it seems that the problem has not been as widespread lately so hopefully they can discover what caused the problem with yours

 

Lol at #4

 

While I understand your frustration, and your right to vent, the 2UR-GSE is an overbuilt engine. If you had a TB issue, maybe you are just unlucky.

HOWEVER, with that in mind, Lexus COULD be blowing smoke because Toyota got caught with their hands in the candy jar when it comes to their V35-FTS that comes in the Tundra and certain LX and GX Lexus SUVs. They lied about the issue with these engines saying it was metallic shavings from the factory that were causing the issue when in fact it was something else entirely (and worse).

This video breaks it down and it's pretty damning for Toyota.

 

You could have an unrelated issue or just a one-off defect. It’s understandable to be all worked up and frustrated but it’s under warranty and they’ll take care of it I’m sure. Of all the issues out there; exhaust leaks, bumper separation, transmission jerkiness, throttle body, many of us have had no issues whatsoever (knock on wood). It’s a solid car but nothings perfect.

 

InfraGhost_I know nothing about engines yet I always enjoy watching engines being opened like this and seeing how complex yet amazing these operate.....This was very informative

 

You're right to be frustrated - no doubt Lexus is spewing BS. I've seen this company decline and this is just part of that story.

But this doesnt make the 2UR-GSE unreliable. Even out of warranty a TB replacement + labor typically costs ~$500. Generally, unreliable engines refers to catastrophic failure - major internal mechanical damage where the engine needs to be entirely replaced. Think Hyundai and Kia.