Join Date: Jan 2009
Not sure about the diagnostics bit. (I need to do buy that too.) But i had the noisy tappets on start up too for a while.
Now, i may get some grief for this, but i put Slick50 in during an oil change about 40, 000 miles ago and haven't had that noise since! Although i always switch to MAR before putting my seatbelt on, then starting it, just to give it time to wake up.
Some peolpe swear by it and others warn against it, but ive used it in all my cars and its always worked a treat.
May be worth giving it a go.
Good luck with the warning light...