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I don't know why but I can contribute that we have 4 cars, ranging from 1998-2011, so our newest car is 8.5 years old. The LS is the only car that has a sagging driver's seat. This, does not agree with your situation, as you have it on both.
A friend's theory, and I think I buy it, was that the reason is ventilated seats having holes in the cushion, meaning not just pores, but holes, allow it to weaken faster than normal. My mfg. 10/06 BMW (13 months newer than the LS) has sport seats that are hard as rocks. They are not ventilated. But, my front pass seat on the LS is firm. So to me, it still takes use to make it sag.
Thanks John, Anyone else out there have any knowledge on the LS front seat cushions ?
After the first long drive in my 05 LS it is apparent both front seat base cushions have deteriorated. This surprised me as the car has only done a genuine 45,000 kilometres. I read some here who suggest seat cushions are worn out, hence this thread regards cushion replacement. With low klms on my car I don't believe the cushions are worn from use but what I do suspect is that after 15 years, irrespective of use, the cushions deteriate from old age. Anyone agree with this theory ?
i have done more research on the comfort of the seat base and maybe my original thinking regards the deteriated seat bases was wrong.
What I'm now lead to believe is they are infact built this way, Lexus possibly emulating European manufacturers with a firmer base design.
I'm now thinking just get a good memory foam or similar pad to add comfort.
Anyone have recommendations for a good cushion sit on top of seat base ?
I cut a two inch thick open cell foam to fit the base, and then put an inexpensive aftermarket seat pad on top of that which has a color reasonably close to the tan leather. The two combined make the car quite comfortable.
I am not sure I agree with the previous statement "What I'm now lead to believe is they are in fact built this way, Lexus possibly emulating European manufacturers with a firmer base design." I have sat in the passenger seat and it is very comfortable compared to the worn out drivers seat, and my wife has not complained of the passenger seat once.
I cut a two inch thick open cell foam to fit the base, and then put an inexpensive aftermarket seat pad on top of that which has a color reasonably close to the tan leather. The two combined make the car quite comfortable.
I am not sure I agree with the previous statement "What I'm now lead to believe is they are in fact built this way, Lexus possibly emulating European manufacturers with a firmer base design." I have sat in the passenger seat and it is very comfortable compared to the worn out drivers seat, and my wife has not complained of the passenger seat once.
Thanks for your reply.
Another reason for thinking the seat cushions may not be detiorated but are in fact original condition is that they for feel fine up to 2 -3 hours driving. Only after that do both myself and wife feel discomfort in the cushions (bum). That and the car is only genuine 45,000 kilometres. It may be just that my old bones are not what they used to be.
Anyway other thoughts on adding an on top cushion would be appreciated.
I've decided to replace my seat cushion with a new Lexus OEM cushion. Doing this repair now. Comfort aside, I'm tired of the addition of a top cushion, it's just a band-aid, and does not befit the luxury of this car.
One thing I will add to the instructions that are linked to in the Post 1 in this thread (Thank you for posting it !) , it says: "With the fore-aft seat adjusters unbolted from the frame, you can move the seat base back and forth to align the rear bolts with the hole in the frame. Remove the rear bolts from either side."
In order to access the the rear bolt on the right hand side the air duct is in the way, as is the seat belt anchor. I took the seat belt anchor off and undid the screws holding the air duct so that I could get the duct out of the way to access the bolt after I lined it up with the hole in the frame. The fore/aft movement of the seat to get this alignment takes some practice, grab the frame in front and push seat back and forth to do the alignment.
One other point: my smallish diagonal cutters I had (new from the local hardware store) were no match for the metal hog rings. A good twist from a pair of needle nose pliers was sufficient to get them off the wires in the cushion. If I were to do this again I would invest in a good, extra sharp, and larger pair of diagonal cutters. It would make this aspect of the job MUCH easier.
Post Mortem: Having finished this project now, a few other tips for those tackling the job: a pencil magnet or the like is helpful tool. Both long (10 inch) and stubby philips screwdrivers are also needed. I kept track of the fasteners in a little box with dividers for fasteners for the different steps. Putting the seat back in I went via back door, seat bottom first.
Intial reaction - well worth the effort and cost. When I took the new foam out of the packaging I thought geez this feels like the old foam, but when the seat was fully assembled it provided much more support in the middle of the seat than the old one.
Last edited by TominPT; Jul 11, 2020 at 05:46 PM.
Reason: added post mortem
Who else has done this? I am not desperate, but about to order the cushion on the Bell Valentine's sale. This looks tricky to me, but?? I don't have a lot of room to work in my tiny garage, and it seems like there is some trickery that has to happen here. On a scale of 1 to 5, my DIY is a 2/2.5.
If you didn't do it yourself, would you take it to a dealer or an upholsterer?
Last edited by CA2WALS430; Feb 12, 2026 at 03:59 PM.
Hey John,
You're right - worse case scenario is you put the foam back on the base, throw it all back together, and drive it to an upholstery shop.
I don't like answering questions with questions, but (1) is this your only means of transport, and (2) if you run into a problem when you're working on cars, do you tend to freak out? If yes, then I might let the professionals handle it. If not, then I say dive in. I have the luxury of the LS being an "extra" car for me so I can afford to work on it at my own pace.
Either way you decide to go - good luck and have fun!
This might answer my question. @Johnhav430 , what did you do?
Who else has done this? I am not desperate, but about to order the cushion on the Bell Valentine's sale. This looks tricky to me, but?? I don't have a lot of room to work in my tiny garage, and it seems like there is some trickery that has to happen here. On a scale of 1 to 5, my DIY is a 2/2.5.
If you didn't do it yourself, would you take it to a dealer or an upholsterer?
Hi All, this one got buried, but I got the cushion and while my thought was to store it, I'm kind of excited and might pursue this sooner. Does anyone have thoughts or recommendations on my question?
I think the upholsterer might be cheaper but the dealer would have the detailed instructions about wiring and placement?
Last edited by CA2WALS430; Feb 21, 2026 at 09:27 AM.
I have a new to me 05 that I love but I’m experiencing the right side buttock pain that so many others have described (apparently even when they were new). I’ve seen the seat bucket without a cushion and the design is the clear explanation as the frame is different and more protrusive on the right side. I don’t think the foam on my seat is all that broken down so I’m hesitant to replace it with an oem cushion. Anyone else experienced this? Would appreciate suggestions!
when i replaced my leather seat cover ( and new OEM foam) i added 1/2 inch of additional foam under the pad. and it helped a bit. I still think the LS430 seats are hella uncomfortable, and it's my least favorite part about the LS430
when i replaced my leather seat cover ( and new OEM foam) i added 1/2 inch of additional foam under the pad. and it helped a bit. I still think the LS430 seats are hella uncomfortable, and it's my least favorite part about the LS430
The passengers seat is also hard as a rock in my car even though interior looks absolutely perfect. The back seat however is very comfortable. I don’t think anyone had ever sat back there before I bought it. That makes me think new foam may help. Just hate to go through the process to replace and the expense involved if it won’t do much. It bothers me enough that I’m considering selling the car. If I drive for more than an hour it’s legitimate pain that lingers for hours afterwards. A shame because otherwise it’s great in every way.
