It's a torx security screw; there's a little nubbin in the center to keep normal torx tools out.
You need a torx security bit with the hole in the center to turn it. (I seem to recall it's T20? Not sure.)
On my bike these went immediately into the trash and were replaced with M5 allen head screws.
And there are two of them on each TPS.
2002 Suzuki DL1000 V-Strom, Dark Metallic Space Blue
1983 Suzuki GS850G, Cosmic Blue
2005 KLR685, Aztec Red - Turd II.2, the ReReTurdening
Last edited by bwringer; 05-20-2019 at 07:17 PM.