My 2025 TX350 has developed an annoying knock/clunk in the right rear corner.
From day one, there was a structural creak at low speeds when driving over uneven ground.
Now it’s progressed into a regular knock/clunk.
I suspect it’s a comprised gusset that has a manufacturing defect or possibly even a design flaw.
Anyone else having this issue ?

 

I have a 2026 TX500h and didn't notice that issue on mines. So far so good.

Is the issue reproduceable every time? If so, bring to dealer to get that fixed under warranty.

 

I do not notice this on my 12,000 mile '25 TX350.

 

In my 2024 TX, I had that same creek/popping noise when backing out of the driveway or going over uneven surfaces. Started around 17k miles and like you, got worse.
Although frustrating to deal with and went to the dealership multiple times, it was finally fixed.
They had to adjust the pano sunroof track that was loose and the body needed some shimming or welding around the sunroof assembly. Lexus had to send the car to their body shop to take the headliner and associated parts apart to do the repair. Kudos to them, everything is still scratch and rattle free. 5k miles later, still rattle and squeak free.

 

It sounds like your rear suspension creaking.

 

3,000 miles and solid as a rock, quiet and comfortable....

 

No such problem on mine, but its VERY new.

Regardless, I've done a lot of suspension and body work on my own cars over the years, and here is my personal opinion ...

FIRST thing to do is to check to see that ALL wheel lug nuts are tightened to spec. It could be as simple as that. I've seem many cars whose tires/wheels have been serviced and the shop simply forgot to tighten up the lug nuts or bolts.

If that's NOT the problem ...

You'll need to have this issue looked at immediately, because it's likely a problem with the driveshafts coming from the rear differential (if its AWD) and/or a broken/loose link in the rear (multilink) suspension - or a worn/failed rubber bushing(s) in the same - or a failed/dry shock absorber/damper.

ANY of these can result is progressive damage or wear to other components - so this needs to be addressed quickly.

It's very unlikely that the car's unibody structure has been compromised, UNLESS there has been significant damage at some point due to an accident and it was improperly repaired.

 

Dealer will replace the entire sunroof structure under warranty.
Dealer states that LEXUS is aware of this issue.
The wind noise & whistling is also accompanied by a knocking noise emanating from the rear portion of the sunroof.

 

On the sunroof comments, I have a 2024 TX 500H without the sunroof. It has 63,000 miles. I had heard that there were certain model levels of the TX could not structurally handle a sunroof so it is no surprise that there may be issues with them.

On the rear suspension, I did not have this problem but did have to replace the rear rack and pinion. Luckily, I had an extended warranty.

I recommend that if you can still obtain the extended warranty if you tend to count on the car for the long term.

 

It's on models with sunroof probably. I was tracking the Grand Highlander forum with sunroof and they have the similar issues.

No problems like that on my TX500h F Sport premium (no sunroof)

 

I have a 2024 TX350 2wd no sunroof with 11,500 nothing like that still runs like new.