light looks like horseshoe upper left stays on

This is your TPMS warning light ( Tire Pressure Monitoring System ). The lamp could be lit for any problem with the TPMS system or sensors. The sensors themselves are inside the tires ( part of the valve stem ), and will cause the light to come on if your tire pressure drops as little as 2 psi so, when you say that your tire pressure is "perfect", be sure that they are no less than 2 psi below the tire pressure for the vehicle which, I think is 36 psi front / 38 psi rear. Have you recently had tires replaced, otherwise completely deflated or, are you running your spare tire ? Not all spares have a TPMS sensor which, if youre running your spare and it has no sensor would cause your light to be on. If youve had tires replaced ( or completely deflated ), the TPMS wheel sensors would have needed to be reset -- Reputable tire centers, etc. would know this and do it without having to say anything but, taking your vehicle to "Joe's Garage" or "Jim's Used Tire Center" or, to your neighbor's to have the tires mounted, chances are the TPMS sensors did not get reset because they either didn't know or didn't have the required tool. The other possibility is that you have a failed wheel sensor which are readily available and aren't too expensive -- $50 - $75 per sensor. Hope this helps.