I don't know much about the mechanical aspect of car ownership so I need some help here.
I went to my independent mechanic yesterday for 3 year brake fluid change on my wonderful 2021 ES 350. When I came back for the car he said all went well and the car looks terrific. However, he said that there is a set of 4 nuts and bolts underside. Something like near the manifold and header (at that point my eyes glazed over). He said one bolt and nut is missing. There were only three and a hole for the fourth. He surmised it was never put in during manufacture because it would be unusual for such a thing to lossen and drop out. He said there is no problem, no oil leaking or any difficulties at all but the fourth screw and bolt should be inserted. I asked him if he could order one and do it. He said he was sure it would be under warranty and check with Lexus. He said should be a very minor item but should be attended to.
A round trip to my Lexus dealer involves 100 miles of travel for them to "check it out." Might there be some oddity here with only three bolts being the norm (like only one plastic terminal cover on the battery)?
Is my mechanic correct?

 

I'm curious to see where it is

 

I swear I recall seeing a similar post in another thread but can't find it at the moment. It was a non-issue though I do recall - of course not sure if it's the same as you are referring to.

 

If a trusted mechanic says it should be attended to, then talk to Lexus if it's still under warranty. It's obviously not critical because it could have been missing for years....

 

Think hard—-please. I’ve you tubed video of underside of our car and couldn’t spot a four hole area. If your memory disgorges the thread, please advise. Could save me an unnecessary trip to Lexus. Wonder, if, in the event it’s as designed, they would charge me for having checked it?

 

A set of 4 nuts/bolt underneath is a bit puzzling. If he mentioned "header or manifold" it makes me think the connection between the integrated exhaust manifold and catalytic converter or catalytic converter to lower j-pipe exhaust (highlighted).



However, it looks like the cat is connected with 5 bolts to the integrated exhaust manifold (essentially directly to the block).

Usually a missing bolt in an exhaust component comes with an audible noise such as a deep throbbing or rumbling from an exhaust leak. If you're not hearing that, then that's probably not the culprit.

That's a weird one. I'm not sure what else it could be from the limited diagrams that the Lexus parts dealers offer online.

 

I’m going to make an appointment with the mechanic for next week, have him put the car up on the rack and take a photo. Then I’ll post the photo and/or e-mail it to the Lexus tech. Then we can see what we’re dealing with.

 

Called mechanic. Mechanic states:
“On the back manifold leading to the head—-rear down pipe where it bolts on to the head. Looks to be four holes and only three have screws and bolts in the hole. If there should be four and all four holes should be filled. If so, Lexus should do it under warranty.”
Make sense?

 

It seems like it could be a bolt holding the exhaust to the cylinder head. If that's the case, you should get this fixed.

 

Certainly will. Odd that it got through inspection that way. I only have 12,000 miles on the car. It wouldn’t have come loose. Also, the Lexus dealership changed the oil halfway through that and didn’t spot it. Very odd situation.
I will, of course, have attended to ASAP.

 

I'd like to know if the nut and bolt came loose, or there have never been one.

Either way, this car needs a safe inspection all over.

I'd conduct some online research or ask your mechanic to provide a detailed list of potential damages that may occur if that particular component comes loose. Have your lawyer sent a letter to Lexus USA, welcome to the US

 

I am sure it would leak if the screw is missing.

 

Mechanic says not to worry. Nothing leaking or loose or making any noises. Just the same, he advises, make an appointment to have the screw installed under warranty or to have Lexus certify on the work order receipt that (for some strange reason), it's a hole that is to remain unused. Like the lack of a cover over the second battery terminal, cars do sometimes have oddities to them. So, who knows. Will have it checked out promptly.
Incidentally, I am my lawyer and PA law requires that I act with reasonable diligence---which I shall, indeed, do.

 

Without a picture or you know exactly what your mechanic is talking about a trip to the Lexus dealer may be futile as the Lexus mechanic might be looking in wrong area. If you or someone else can crawl under car and take picture or carry back to mechanic for picture. Then contact Lexus service and send it to them. This may avert an unnecessary trip.

 

Yep. That's the plan. Thanks for your thoughts.