And the Soarer 4.0 had a GREAT engine!
Best ever. I assume it was in the LS 400 too?
( It had TEMS/ Air Suspension too. Felt like a sofa on wheels - but fast )
Drove my wife's Volvo S80 once - nice car...
On day - wack!
The wing mirror was hit and folded in.
I folded it back out and did it work? It did. It was fine. Amazingly tough!
If it was me ... and assuming you have no warranty to call on... being non-technical...
I'd call in at my local, friendly Lexus/Toyota specialist. Get them to diagnose it perhaps?
( Do you mean no error codes, or no means to read them? )
I'm sure they do, and with the MOT. I get those done at the same time.
But if in doubt just ask them to check something specific as well.
They do for me - no extra cost.