The engineers at Lexus are evidently sadists because replacing the fog light bulb on a SC430 is a BEAR of a job! With that colorful disclaimer issued, however, this is how you would go about changing the fog light bulb: Raise one front corner, remove all bolts under the car that attach the corner under-car shroud. Pull it back into the wheel well. Once you finally get to the housing itself, you must disconnect the plug, then you have to unclip the bulb which is snapped in then remove the bulb, reverse and you're done.
It is helpful to have a small mirror to assist you in seeing the clip that holds the light in the socket. Each side took me almost two hours. You'd think the second side would be easier but I had a much harder time with the clip holding the bulb in.
Since you're going through all of this agonizing pain anyhow, I would advise replacing the fog lamp bulbs with an OEM replacement unit. These can be purchased for under $20 at most genuine OEM Lexus parts e-tailers.
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