IT IS NOT DUFF O2 SENSORS & ECU "UPGRADE" REQUIRED!!!
It IS the petrol cap, plain and simple.
Next time, push down as you twist on, and give it a few extra clicks.
If you're still getting warning lights, buy a new cap first and see if it still remains after that.
For further anecdotal proof the warning systems Lexus have decided to employ being less than thoroughly thought through, I give you the SRS Airbag light.
Mine has been on more than off in recent weeks, without any rhyme or reason, but first appeared when I'd given the car a good thorough wash and rinse, and treatment.
Thought I'd screwed up a parking sensor, but had a stored code cleared the other day, relating to the day I ran out of petrol.
Quickly skipping past that tidbit of numptyism, SRS bag was off when the ex-Toyota mechanic plugged in the baby ODB reader, and after clearing it, plugged in the big £7K Snap on version to see if it could show up anything else.
Nothing showing, they left it at that, and I said I'll see how it went from thereon in.
Still no SRS Airbag light displaying after the System Check has completed - so I can only conclude the timing as coincidental when it appeared, and it was being used to indicate a code stored rather than an actual airbag/PDC sensor issue.
So, don't be sweating bullets just yet - you've two things you can try first before resigning yourself to there being something else at play.
Just be vigilant on the oil level - I'm 3K miles in on mine, nearing the 80K service, and already I've topped up with 1.5L of oil.
Engine will be getting flushed and refilled with 5W-30 or 40, and monitored for consumption then.
If it's still drinking it, then I will be inviting Lexus to prove I don't have the sticky ring issue some Club Lexus members have had, and seems to have resulted in an unlimited mileage drivetrain warranty extension.
I love this car, but as much as there's a number of elements copied from the BMW E65 7 Series from '02, it's nowhere near as informative/smart, and that's before touching upon the asthmatic seat ventilation fitted!
So, to reiterate, put your cheque book down - it's a tad premature to be waving it about, at the moment.